Answer Key for EV-2000_053348 Electric Vehicle Thermodynamic Systems Trainer Teacher Only 91-EV-2000_REVB © ConsuLab Educatech Inc, 2026. All rights reserved. 91-EV-2000 Table of Contents 400-6330 Zéphirin-Paquet St. Québec QC G2C 0M3 Canada consulab.com info@consulab.com Toll-free: +1 (800) 567-0791 USA: +1 (810) 222-4525 Canada: +1 (418) 688-9067 Fax: +1 (418) 843-3444 2 Table of Contents Tips for Operating the Trainer 5 Student Assignments Instructor Notes and Answers 6 General Instructor Note 7 Environmental Impact of Answer Key 7 SA-1 - LEVEL I — Components of an EV Thermal Management System 8 Instructor Notes 8 Answers 9 SA-2 - LEVEL I — How a Scroll Compressor Works 12 Instructor Notes 12 Answers 13 SA-3 - LEVEL I — Superheating and Subcooling 16 Instructor Notes 16 Answers 17 SA-4 - LEVEL I — Cooling the Cabin 22 Instructor Notes 22 Answers 23 SA-5 - LEVEL I — Heating the Cabin 25 Instructor Notes 25 Answers 26 SA-6 - LEVEL II — Electronic Expansion Valves 28 Instructor Notes 28 Answers 29 SA-7 - LEVEL II — Cabin Heat and Defrost 31 Instructor Notes 31 Answers 32 SA-8 - LEVEL I — Heating the Cabin Without Refrigerant 35 Instructor Notes 35 Answers 36 Section 1 - Cabin Components Assessment 38 SA-9 - LEVEL II — Effects of a Restricted Expansion Valve 40 Instructor Notes 40 Answers 41 SA-10 - LEVEL III — Restricted vs. Blocked Expansion Valves 45 Instructor Notes 45 Answers 46 91-EV-2000 Table of Contents 400-6330 Zéphirin-Paquet St. Québec QC G2C 0M3 Canada consulab.com info@consulab.com Toll-free: +1 (800) 567-0791 USA: +1 (810) 222-4525 Canada: +1 (418) 688-9067 Fax: +1 (418) 843-3444 3 SA-11 - LEVEL III — Diagnosing the Evaporator 49 Instructor Notes 49 Answers 50 SA-12 - LEVEL III — Diagnosing a Cabin Performance Concern 54 Instructor Notes 54 Answers 55 Section 2 – Cabin Flow Assessment 58 SA-13 - LEVEL I — Introduction to Battery Cooling 60 Instructor Notes 60 Answers 61 SA-14 - LEVEL II — Battery Cooling with HVAC 63 Instructor Notes 63 Answers 64 SA-15 - LEVEL I — Introduction to Battery Heating 67 Instructor Notes 67 Answers 68 SA-16 - LEVEL II — Glycol Heating System Performance Analysis 70 Instructor Notes 70 Answers 71 SA-17 - LEVEL II — Heat Transfer from the Battery to the Cabin 74 Instructor Notes 74 Answers 75 SA-18 - LEVEL III — Abnormal Heat Transfer 77 Instructor Notes 77 Answers 78 Section 3 – Battery Flow Assessment 81 SA-19 - LEVEL II — Battery Cooling Strategies and System Prioritization 84 Instructor Notes 84 Answers 85 SA-20 - LEVEL II — Battery and Cabin Cooling 88 Instructor Notes 88 Answers 89 SA-21 - LEVEL III — Diagnosing Glycol Performance 90 Instructor Notes 90 Answers 91 SA-22 - LEVEL III — Diagnosing Battery Cooling Performance 94 Instructor Notes 94 Answers 95 91-EV-2000 Table of Contents 400-6330 Zéphirin-Paquet St. Québec QC G2C 0M3 Canada consulab.com info@consulab.com Toll-free: +1 (800) 567-0791 USA: +1 (810) 222-4525 Canada: +1 (418) 688-9067 Fax: +1 (418) 843-3444 4 © ConsuLab Educatech Inc, 2026. All rights reserved. No part of this work may be reproduced or transmitted in any form by any means, electronic, mechanical, including photocopying and recording, or by any information storage or retrieval system, without written permission from the publisher. Printed in Canada. The content of this manual is applicable to models 053348 and above. SA-23 - LEVEL III — Restricted vs. Blocked Chiller Feed 98 Instructor Notes 98 Answers 99 SA-24 - LEVEL III — Diagnosing Heat Rejection Limitations 101 Instructor Notes 101 Answers 102 SA-25 - LEVEL III — Diagnosing Cabin Evaporator Flow Limitations 105 Instructor Notes 105 Answers 106 SA-26 - LEVEL III — Diagnosing a Severe Cabin Cooling Failure 109 Instructor Notes 109 Answers 110 SA-27 - LEVEL III — Diagnosing a Cabin Heating Limitation 113 Instructor Notes 113 Answers 114 Advanced Battery Flow Section Assessment 117 Diagrams and Schematics Mode 1 = Cabin Cool : Heat Pump 120 Mode 2 = Cabin Heat : Heat Pump 121 Mode 3 = Cabin Heat + Defrost : Heat Pump 122 Mode 4 = Cabin Heat : PTC + Glycol Radiator 123 Mode 5 = Battery Cool : Glycol Radiator 124 Mode 6 = Battery Cool : HVAC 125 Mode 7 = Battery Heat : PTC + Glycol 126 Mode 8 = Cabin Heat & Battery Cool : HVAC 127 Mode 9 = Battery Cool : HVAC + Glycol Radiator 128 Mode 10 = Cabin Cool + Battery Cool : HVAC + Glycol Radiator 129 Blank Diagram With ID 130 Fault Schematic 131 Glossary 132 consulab.com info@consulab.com 5 91-EV-2000 Tips for Operating the Trainer Tips for Operating the Trainer 1. To measure and calculate accurate superheat, wait 3 minutes after selecting a mode. The system needs time to stabilize and allow the EEVs to adjust as intended. 2. If the system is operating in any mode other than Mode 2 or Mode 3, and the high-side pressure is greater than or equal to 190 psi, then switching to Mode 2 or Mode 3 will prevent the compressor from starting until the high-side pressure drops below 190 psi. This normally takes approximately 3 to 5 seconds. This strategy is used to protect the system. 3. In Mode 6, the external heat exchanger fans are modulated based on low-side pressure in order to stabilize system pressures. This is an excellent teaching point to demonstrate how the system reacts according to the heat absorbed by the glycol coming from the high-voltage battery. 4. In Mode 8, the cabin condenser fans are modulated based on low-side pressure in order to stabilize system pres- sures. 5. The fault box keeps faults in memory!!! For example, if Mode 1 is selected and Fault 1 is activated, the fault be- comes active and affects the product as expected. However, if the mode is changed to Mode 2 and Fault 1 is not applicable in that mode, the F1 LED in the fault box will flash, but the system will operate normally in the new mode without the fault being active. If Mode 1 is selected again, Fault 1 will become active again. If a fault is active and the system is switched to another mode where that fault is applicable, the fault will remain active and continue to affect the system. 6. There are two filters on the product that are used to protect the three EEVs in case particles are present and could potentially block one or more EEVs. 7. When operating in Mode 3 with Fault 9 and/or Fault 12 applied, there is little to no impact on system pressures. The only way to diagnose the problem is to use a thermometer and confirm that there is no fan operation at the cabin evaporator. 8. When operating in Mode 2 and/or Mode 3 with Fault 1 active, after a certain amount of time, usually after 6 to 10 minutes, superheat may become very low and can sometimes even become negative. This can happen because the EEVs have a minimum opening value they can reach in order to prevent the compressor from entering a vacuum condition. In a real vehicle application, a scroll compressor would normally vary its rotational speed instead. consulab.com info@consulab.com 6 91-EV-2000 Student Assignments Student Assignments Instructor Notes and Answers consulab.com info@consulab.com 7 91-EV-2000 General Instructor Note & Environmental Impact of Answer Key General Instructor Note To increase observable temperature and pressure deltas in the answer key data, instructors may briefly operate the EV-2000 in the opposite functional mode first (for example, warm the battery before switching to Battery Cool), allow- ing components to start from a higher or lower thermal state and making system trends more apparent to students. Environmental Impact of Answer Key The pressures and temperatures provided in the EV-2000 answer key are approximate and are intended to show ex- pected system trends, not exact values. Actual readings will vary based on environmental conditions such as ambient temperature, humidity, airflow, and system starting conditions. When grading, focus on whether student measurements follow the correct trends and relationships indicated in the answer key (for example, increasing, decreasing, or stabi- lizing behavior). Values that reasonably align with these trends — typically within about ±10% — should be considered acceptable evidence of understanding. consulab.com info@consulab.com 8 91-EV-2000 SA-1 - LEVEL I — Components of an EV Thermal Management System SA-1 - LEVEL I — Components of an EV Thermal Management System Instructor Notes Objective: Students will label all components in an electric vehicle thermal management system. Teaching Suggestions • Keep it physical. Students learn the fastest by touching components, visually comparing them, and seeing the pipes/ hoses/heat exchangers up close. Encourage them to walk around the trainer instead of labeling from memory. • If your class is large give a few magnets to each student or pair of students, so they all have a chance to physically place a label. Or have some of the class start with Part 3, while another half starts with Part 1, so they can all place labels. • When students are labeling components, remind them that the left side of the EV-2000 trainer represents the front of the vehicle and the right side represents the inside of the cabin. They can confirm this by looking at the yellow car diagrams across the top of the trainer, which show the vehicle orientation and airflow direction. • Group Vocab by Function. Instead of going alphabetically, group terms into families. Example: - Heat exchangers: evaporator, condenser, chiller - Flow controllers: compressor, expansion valve - Supplemental heat: PTC heater - Support components: pump, accumulator, radiator • Take the chance to gamify it. “Point to the ___” — call out a component and have pairs or a team representative race to or point to it. • Lead them to the right word. When students are stuck, guide using function based clues, not location clues (“Which of these components absorbs heat?”) or direct them to look up the word in the glossary. • Common mix ups to watch for: • Students confuse evaporator vs. condenser because both look like heat exchangers. • Emphasize the rule: “Cold side = evaporator absorbs heat; hot side = condenser releases heat.” • Students may misidentify the chiller as a condenser. Point out the glycol loop connections. Practical Applications • Real service work uses this language. Every OEM manual, HVAC diagram, and diagnostic chart depends on these exact terms. • Miscommunication = misdiagnosis. Confusing evaporator and condenser leads to completely wrong conclusions about pressures, temperatures, or system faults. “If you can’t name it, then you can’t diagnose it.” consulab.com info@consulab.com 9 91-EV-2000 SA-1 - LEVEL I — Components of an EV Thermal Management System Answers Objective: Label all components in an electric vehicle thermal management system. Material Required: EV-2000, magnetic component labels, EV-2000 Glossary of Terms Part 1 – Component Labeling Correctly identify each component on the EV-2000 trainer and place the matching label in the correct location. Components to Identify : • Compressor • Cabin Condenser • Airflow Shutter • Expansion Valve (3x) • Bypass Valve (5x) • External Heat Exchanger • Cabin Evaporator • Chiller • Accumulator • Bulkhead • Pump • PTC Heater • Heater core • Battery • Radiator Instructions: 1. Walk around the trainer and locate each physical component. 2. Place the magnetic labels near the component it represents. 3. Try matching component shape, piping, heat exchanger location, or appearance or review the Glossary for support. 4. Check with the instructor before moving on. Part 2 – Label the EV-2000 Diagram Using the same component list from Part 1: 5. Label each component on the worksheet diagram. 6. Use correct EV-2000 term, spelling matters, so use the list above and/or glossary for support. consulab.com info@consulab.com 10 91-EV-2000 SA-1 - LEVEL I — Components of an EV Thermal Management System 7. The diagram should reflect the physical layout as seen on the trainer. 8. Check your work with your instructor before moving on. EV -2 0 00 - B LA N K S C H EM A T IC © C on su La b Ed uc at ec h In c, 2 02 6. A ll ri gh ts r es er ve d consulab.com info@consulab.com 11 91-EV-2000 SA-1 - LEVEL I — Components of an EV Thermal Management System Part 3 – Vocabulary Skill Builder Quick Match Match each component to the correct description: 1. Evaporator D 2. Condenser A 3. PTC Heater C 4. Chiller B Choices: A. Releases heat to outside air (heating effect) B. Transfers heat between glycol and refrigerant loops C. Electrically heats glycol or cabin air D. Absorbs heat from cabin air (cooling effect) Glossary Hunt Write a 1 sentence definition for the words below. The goal: make the definitions simple and clear, like for a beginner technician. 5. Evaporation: The cooling effect when the refrigerant changes state from a liquid to a vapor, because it absorbs latent heat. 6. Condensation: As the refrigerant changes state from a vapor to a liquid, it creates a warming effect because it releases latent heat. 7. Saturation: That moment when refrigerant can be a liquid and a vapor because it is actively condensing or evaporating. 8. PSIG: The amount of pressure the system has on top of normal air/atmospheric pressure. Compare and Contrast Using the definitions in the glossary as a reference, circle the correct words to explain the difference between sensible heat and latent heat. 9. Sensible heat can/cannot be measured with a thermometer and causes a change in temperature/state without a change in state. 10. Latent heat can/cannot be measured with a thermometer because it is absorbed or released during a change of temperature/state. consulab.com info@consulab.com 12 91-EV-2000 SA-2 - LEVEL I — How a Scroll Compressor Works SA-2 - LEVEL I — How a Scroll Compressor Works Instructor Notes Teaching Suggestions • Bring attention to the scroll motion. Students often struggle to visualize how the scrolls move. Use the “two snail shells” analogy and demonstrate with your hands: one stationary, one moving in a small orbit. Explain that the refrig- erant is squeezed into a smaller pocket as the orbit continues. This is compression. • Keep the focus on vapor only. Remind students repeatedly that compressors are vapor pumps and cannot com- press liquid. This will help teach superheat in SA 3: “The refrigerant MUST be a superheated vapor when it reaches the compressor.” • Tie pressure and temperature together explicitly. When students read the suction and discharge gauges, guide them in converting PSIG → saturation temperature. This helps them understand why discharge temperature rises, not just because it’s “hot,” but because compressing vapor increases both pressure and saturation temperature. • If the system is operating in any mode other than Mode 2 or Mode 3, and the high-side pressure is greater than or equal to 190 psi, then switching to Mode 2 or Mode 3 will prevent the compressor from starting until the high-side pressure drops below 190 psi. This normally takes approximately 3 to 5 seconds. This strategy is used to protect the system • Keep students oriented in Mode 1. Point out where the compressor sits in the Mode 1 flow path and remind stu- dents: - Compressor → Condenser (high side) - Evaporator → Compressor (low side) • Emphasize “cause and effect.” Whenever a student identifies a hot discharge line, ask: “What CAUSED that?” Lead them to connect compression → higher pressure → higher temperature. • Watch for common misconceptions: Students may think the compressor “creates heat.” Clarify that the heat rise is a side effect of compression (sensible heat). • Students may say the compressor “pulls” refrigerant through the evaporator. Clarify that pressure difference moves refrigerant; the compressor only creates that difference. Practical Application Notes • Every OEM AC or heat pump diagram relies on understanding low side vs high side conditions. • Misunderstanding compressor function leads to incorrect assumptions about charge levels and superheat/subcooling. consulab.com info@consulab.com 13 91-EV-2000 SA-2 - LEVEL I — How a Scroll Compressor Works Answers Objective: I can explain how a scroll compressor operates and use pressure temperature measurements to describe its effect on the refrigeration cycle. Materials Required: clamp-on thermometer Part 1 – Exploring How a Scroll Compressor Works A scroll compressor has two spiral-shaped scrolls: one stays still, and the other moves in a small circular motion. As the scrolls move, they trap refrigerant vapor and squeeze it into a smaller and smaller space, which makes the vapor hotter and higher pressure. This pressure difference is what allows the system to evaporate refrigerant on the low side and con- dense it on the high side. As the system is running in cooling mode (Mode 1), use these three clues to understand what the compressor is doing: • Suction line = This is the low pressure, cool, heat-laden vapor entering the compressor • Discharge line = This is the high pressure, hot, heat-laden vapor leaving the compressor The compressor’s job is to create the pressure difference that allows evaporation (low side) and condensation (high side) to happen. Check for Understanding 1. Before the refrigerant enters the compressor through the suction line, which component does it come from, and what state (vapor or liquid) is it likely in? Why? It comes from the evaporator as a low pressure vapor because a compressor can only compress vapor. 2. After the refrigerant leaves the compressor through the discharge line, where does it go next, and what changed about it? It goes to the condenser and since it was just compressed it is higher pressure, so it is a high pressure, high tempera- ture vapor. 3. PREDICT Since a compressor must pump vapor only, is the refrigerant coming in from the suction line is superheated or subcooled? The refrigerant coming in through the suction line must be superheated vapor because the compressor can only pump vapor, so the refrigerant has to be heated above its saturation point in the evaporator before entering the compressor. consulab.com info@consulab.com 14 91-EV-2000 SA-2 - LEVEL I — How a Scroll Compressor Works Part 2 - Observe and Collect Data In Mode 1 (Cooling Mode), use the pressure gauges and the digital contact thermometer with clamp style probes to collect the system’s temperature and pressure readings. • For pressure, read the values directly from the low side (suction) and high side (discharge) gauges. • For temperature, attach the thermometer clamp to the suction line and the discharge line pipe, making sure the clamp is fully closed and touching metal for an accurate reading. Turn the trainer on to Mode 1 and let it stabilize for about two minutes, then, fill in each blank with the values measured. The Notes column is there to explain why each measurement matters and how it connects to what the compressor is doing. Measurement Location Value Notes Low-side pressure Suction line gauge 25 PSI Vapor entering compressor Suction line temperature Suction line 79° F / 26° C Above saturation High-side pressure Discharge line gauge 150 PSI Hot vapor leaving compressor Discharge line temperature Discharge line 113° F / 45° C Added sensible heat from compression Part 3 – What Does this Data Mean? 4. Why is the suction pressure lower than the discharge pressure? A. The compressor takes low pressure vapor and compresses it to high pressure vapor. B. The refrigerant cools down as it moves through the system. C. The evaporator increases system pressure. D. The condenser pulls refrigerant back toward the compressor. 5. Based on the measurements above, describe what the compressor is doing to the refrigerant. It’s adding heat through compression, increasing the refrigerant’s pressure, and raising its saturation temperature. 6. Which line feels warmer (or has more “sensible heat”), the suction line or the discharge line? Why? The discharge line feels hotter because compression adds heat to the vapor. consulab.com info@consulab.com 15 91-EV-2000 SA-2 - LEVEL I — How a Scroll Compressor Works 7. Technician A measures the suction line temperature as less than 5°F (2°C) above the saturation temperature. Tech- nician A says it’s fine because the refrigerant is mostly vapor and the compressor can handle it. Technician B dis- agrees, saying that being this close to saturation means the refrigerant may still be boiling, and any remaining liquid can damage the compressor. Who is correct? A. Technician A B. Technician B C. Both are correct D. Neither are correct 8. True or False: If the refrigerant is still absorbing latent heat, it is not ready for the compressor, because it isn’t fully vapor yet. True consulab.com info@consulab.com 16 91-EV-2000 SA-3 - LEVEL I — Superheating and Subcooling SA-3 - LEVEL I — Superheating and Subcooling Instructor Notes Teaching Suggestions • To measure and calculate accurate superheat, wait 3 minutes after selecting a mode. The system needs time to stabilize and allow the EEVs to adjust as intended. • Emphasize saturation temperature as the reference point: superheat is above it, subcooling is below it, and phase change occurs at it. • Use the boiling water analogy often: temperature remains constant during a phase change. • Make concepts tangible by having students compare the feel of the suction line (superheated vapor) and liquid line (subcooled liquid). • Reinforce system protection: - Low superheat → liquid may reach the compressor. - Low subcooling → vapor may enter the metering device. • Encourage students to routinely convert pressure to saturation temperature using PT charts or gauge scales. • Watch for common misconceptions: - Saturation temperature is the boiling/condensing point, not a target temperature. - More superheat is not always better; it can indicate a starved evaporator. - Subcooling occurs in the condenser and liquid line, not the evaporator. - In Mode 1, the external heat exchanger is the condenser—refer to the diagram. - Do not compare temperature differences (ΔT) such as superheat or subcooling to actual temperature readings. Practical Applications • OEM service information specifies acceptable superheat and subcooling values, which technicians use to diagnose charge issues, airflow problems, and restrictions. • Superheat and subcooling provide a faster and more accurate picture of system operation than pressures alone. consulab.com info@consulab.com 17 91-EV-2000 SA-3 - LEVEL I — Superheating and Subcooling Answers Objective: Explain superheating and subcooling and identify which component performs each. Material Required: EV-2000, power supply, Mode 1 = Cabin Cool: Heat Pump diagram, clamp-on thermometer Part 1 – Superheat Saturation temperature is pressure (PSIG) convert to temperature. When a gauge reads 119 PSIG à 41°F / 5°C. That temperature value is the saturation temperature of the refrigerant at that pressure. Saturation also means Boiling point Evaporating temperature Condensing temperature Where latent heat happens Where liquid and vapor coexist Where phase change occurs All of these happen at the saturation temperature. So, when the PT chart says the refrigerant is saturated at 41°F, that one temperature means: It’s boiling at 41°F / 5°C It’s evaporating at 41°F / 5°C It’s condensing at 41°F / 5°C Latent heat is happening at 41°F / 5°C Liquid and vapor both exist at 41°F / 5°C Change of state is occurring Imagine refrigerant flowing through the coil out of the evaporator at 41°F / 5°C: During all of that the temperature stays at 41°F / 5°C, because energy is instead being used as latent heat to change the phase from liquid to vapor, not to increase temperature. This is why boiling water stays at 212°F / 100°C until all the liquid is gone. Once the last drop of liquid becomes vapor, then the vapor can rise in temperature. Any temperature rise above sat- uration is called superheat. We calculate superheat to confirm that the refrigerant has fully boiled into vapor before it reaches the compressor. Saturation temperature tells us where boiling should end, but superheat tells us whether it actually did. Too little superheat means liquid refrigerant may still be present and can damage the compressor. Too much superheat means the evaporator is underfed and not absorbing heat effectively. This is why superheat is not just a number, it is a safety and performance check of the evaporator. consulab.com info@consulab.com 18 91-EV-2000 SA-3 - LEVEL I — Superheating and Subcooling Superheat is sensible heat added above saturation. Sensible heat is the heat that changes temperature and it can be measured with a thermometer. Sensible heat is not the heat used to change phase, like latent heat. Example: The saturation temperature is 41°F / 5°C, but the actual suction line temperature is 61°F / 16°C. 61°F - 41°F = 20°F 20°F is superheat 16°C - 5°C = 11°C 11°C is superheat EV-2000 Superheat System Specifications Superheat What It Means System Condition 28 ° C) Too High Evaporator starved; undercharge, restriction, airflow problem, or metering issue NOTE: These values are specific to the EV-2000 trainer and should not be compared directly to calculated superheat ranges used in real world automotive or HVAC systems. Match the words in the word bank to the correct sentence. Definition Word Bank 1. The temperature where liquid and vapor coexist is called saturation. Superheat • Subcooling • Evaporator • Condenser • Saturation • Liquid • Vapor • Latent Heat 2. Sensible heat added above saturation to vapor is called superheat. 3. The component where refrigerant boils into vapor is the evaporator. 4. Hidden heat that can’t be seen on a thermometer, but is energy used to change states is called latent heat. Using the Mode 1 diagram and the EV-2000, locate the following: • The evaporator outlet (where the refrigerant finishes boiling) • The suction line • Low side pressure gauge 5. Take low-side pressure (PSIG). Read the suction gauge and convert PSIG to saturation temperature using the inner R134a scale. 25 PSIG → 29° F / -1.9° C 6. Measure actual suction line temperature. Use a clamp thermometer on the copper line coming out of the evaporator. 77° F / 25° C consulab.com info@consulab.com 19 91-EV-2000 SA-3 - LEVEL I — Superheating and Subcooling 7. Calculate superheat Superheat = Actual suction line temp - Saturation temp 77°F - 29°F = 48° F 25° C – (-1.9° C) = 26.9° C 8. Based on the measurements above and the EV-2000 superheat specifications, is the system flooded, normal, or starved? Why? Based on the measurements and the EV-2000 superheat specifications, the system is operating normally. The calculated superheat is 48°F (26.9°C), which falls within the EV-2000’s normal operating range of 48–59°F (9–15°C). This indicates that the evaporator is being fed correctly and the refrigerant has fully vaporized before entering the compressor. As a result, the system is neither flooded nor starved under these operating conditions. Part 2 – Subcooling Subcooling is sensible heat removed from a liquid below its saturation temperature. Subcooling happens on the high pressure side of the system, after the refrigerant has fully condensed back into a liquid. We calculate subcooling to confirm that the refrigerant leaving the condenser is fully liquid before it reaches the metering device. Saturation tem- perature tells us where condensation ends, but subcooling tells us whether the liquid has cooled enough to stay liquid. Too little subcooling means vapor may enter the expansion valve, causing unstable operation. Subcooling is therefore a charge and condenser performance check. Example: If the refrigerant’s saturation temperature at the condenser outlet is 99°F, and the actual measured liquid line temperature is 89°F: 99°F-89°F=10°F subcooling This means the refrigerant is cooled 10°F below the temperature where it changed from vapor to liquid. EV-2000 Subcooling Specifications Subcooling What It Means System Condition 40 ° F (> 22 ° C) Too High Overcharge, restricted airflow, or condenser flooding NOTE: These values are specific to the EV-2000 trainer and should not be compared directly to calculated superheat ranges used in real world automotive or HVAC systems Using the Mode 1 diagram and the EV-2000, locate: • The condenser outlet (external heat exchanger in Mode 1) • The liquid line • The high side pressure gauge 9. Take high-side pressure (PSIG). Read the suction gauge and convert PSIG → saturation temperature using the inner R134a scale. 150 PSIG à 11° F / 44° C consulab.com info@consulab.com 20 91-EV-2000 SA-3 - LEVEL I — Superheating and Subcooling 10. Measure actual liquid line temperature. Use a clamp thermometer on the liquid line leaving the condenser. 86° F / 30° C 11. Calculate subcooling Subcooling = Saturation temp - Actual liquid line temp Subcooling = 111° F - 86° F = 25° F Subcooling = 44° C - 30° C = 14° C 12. Compare with the subcooling chart Based on the measurements above, how is the system performing? The system is operating normally. The calculated subcooling of 14 °C falls within the EV-2000 normal operating range of 9–15 °C, indicating a properly filled condenser and stable system operation. This diagram illustrates how refrigerant behaves as it moves through the three major temperature–state regions in a cooling system: subcooled liquid, saturation, and superheated vapor. The middle band represents the saturation zone, where liquid and vapor coexist and all added or removed energy becomes latent heat, so the temperature remains con- stant during the phase change. Above this zone, the refrigerant has fully evaporated and any additional heat becomes sensible heat, creating superheated vapor; below it, sensible heat is removed from fully condensed liquid, producing subcooling. 13. Using the Mode 1 diagram, trace the refrigerant path and mark on the diagram where the refrigerant is: • Superheated Students should highlight the low pressure vapor from the evaporator to the compressor. • Subcooled Students should highlight the high pressure liquid from the condenser to the expansion valve. consulab.com info@consulab.com 21 91-EV-2000 SA-3 - LEVEL I — Superheating and Subcooling 14. If the condenser airflow were partially blocked in Mode 1, how would it impact the rest of the refrigerant loop? • Subcooling increases or decreases? • Pressure increases or decreases? Where? • Superheat increases or decreases? Why? If the condenser airflow is partly blocked in Mode 1, the refrigerant can’t cool down properly. This makes the pres- sure on the high side go up because the condenser is getting hotter and can’t get rid of heat like it should. Since the refrigerant doesn’t cool enough to become a fully “subcooled” liquid, subcooling will decrease. Because the evap- orator now gets less liquid refrigerant, it can’t boil as much, so the suction line gets hotter and the system ends up with higher superheat. NOTE: You can check their predictions using Mode 1, Fault 1. 15. Why is the saturation temperature so important for understanding how the refrigerant behaves, and how does the diagram show that everything in the system relates back to this temperature? Saturation temperature is important because it marks the exact point where the refrigerant changes between liquid and vapor. All other temperatures in the system are compared to this one: anything above it becomes superheated vapor, and anything below it becomes subcooled liquid. This makes saturation temperature the reference to under- standing what state the refrigerant is in and how it’s behaving throughout the loop. consulab.com info@consulab.com 22 91-EV-2000 SA-4 - LEVEL I — Cooling the Cabin SA-4 - LEVEL I — Cooling the Cabin Instructor Notes Teaching Suggestions Part 1 – Tracing the Flow to Cool the Cabin • Encourage students not only to color code the refrigerant states, but also to write the labels directly on the sche- matic (e.g., “High pressure vapor,” “Low pressure liquid,” etc.). This helps reinforce vocabulary and ensures they can read and interpret diagrams without relying on colors alone. • Remind them that the refrigerant changes both pressure and state, and that their schematic should visually commu- nicate those transitions clearly. Part 2 – Measuring the Pressure If you only have one EV-2000 available, assign specific roles to maximize engagement and accuracy: • Student 1: Starts/operates the trainer • Student 2: Reads and calls out low side pressure • Student 3: Reads and calls out high side pressure • Student 4: Manages the timer • Student 5: Uses the thermometer • Remaining students: Record the readings into their tables and verify values as a group This structure keeps the entire class active instead of passive. Part 3 – Heat Flow Analysis • Remind students that they have already practiced measuring line temperatures in earlier assignments. Encourage them to look back at their previous data, especially where they saw patterns in suction temperature, liquid line tem- perature, and superheat/subcooling readings. • Emphasize that recognizing saturation, superheat, and subcooling depends on the pressure/temperature relation- ships they’ve already learned. This is where all earlier lessons connect. • Differentiation: For students who may struggle with academic writing, consider assessing Part 3 through a verbal explanation. Invite them to verbally walk you through the refrigerant flow on their diagrams while using the required core vocabulary. This approach maintains rigor while supporting diverse learning needs. Practical Applications • Understanding refrigerant state changes allows technicians to diagnose weak cooling, faulty expansion valves, re- stricted condensers, and low refrigerant charge. • Many hybrid and electric vehicles use reversible heat pump systems like Mode 1. Recognizing how refrigerant flow changes between heating/cooling is essential for modern service work. • Practicing superheat and subcooling verification are some of the most important measurements for confirming proper refrigerant charge and preventing compressor damage, which are core tasks in any professional A/C service procedure. consulab.com info@consulab.com 23 91-EV-2000 SA-4 - LEVEL I — Cooling the Cabin Answers Objective: Trace refrigerant flow through evaporator and condenser and measure low/high-side pressures during cool- ing. Material Required: EV-2000, power supply, Blank Schematic with ID diagram, digital probe thermometer Part 1 – Trace the Flow to Cool the Cabin Use the Blank Schematic with ID diagram to complete the following: 1. Draw arrows showing the refrigerant path starting from the compressor Label and color where the refrigerant is: - RED: high pressure vapor - YELLOW: high pressure liquid - DARK BLUE: low pressure liquid - LIGHT BLUE: low pressure vapor 2. Identify in which component the refrigerant “absorbs heat” as the evaporator 3. Identify in which component the refrigerant “releases heat” as the condenser 4. Label where subcooling occurs 5. Label where superheat occurs 6. Put an X on any components not used during this mode. 7. Check your work with your instructor before moving on. Part 2 – Measure the Pressure Measure how suction and discharge pressures change over time as the system cools in Mode 1. Follow the steps below to record data. Start the trainer in Mode 1: Cabin Cooling: Heat Pump and let it run from a cold start. Record suction and discharge pressures every 30 seconds for 2–3 minutes. Fill in the table below: Time (s) Suction Pressure Discharge Pressure Evaporator Air Temperature 0 15 PSI 125 PSI 66° F / 19° C 30 20 PSI 140 PSI 61° F / 16° C 60 25 PSI 150 PSI 52° F / 11° C 90 25 PSI 150 PSI 48° F / 9° C 120 25 PSI 150 PSI 48° F / 9° C consulab.com info@consulab.com 24 91-EV-2000 SA-4 - LEVEL I — Cooling the Cabin Part 3 – Heat Flow Analysis Using the diagram and pressure table data, explain how Mode 1 cools the cabin in at least 5 steps using the following vocabulary: superheat, subcooling, compressor, high pressure liquid, high pressure vapor, low pressure liquid, low pressure vapor, saturation, evaporator, condenser, external heat exchanger. 1. High pressure vapor leaves the compressor exiting at approximately 150 PSI and passes through the cabin condens- er, which is not active in this mode. 2. The high pressure vapor then reaches its saturation temperature inside the external heat exchanger, which acts as the condenser in Mode 1 and releases heat to the outside air. 3. The resulting high pressure liquid leaves the external heat exchanger and enters the expansion valve, where it is metered down to a low pressure liquid. 4. This low pressure liquid enters the evaporator, reaches its lowside saturation point, absorbs heat from the cabin air, and leaves the evaporator air outlet at approximately 48° F / 9° C. 5. The refrigerant then becomes superheated low pressure vapor at the evaporator outlet and flows to the accumula- tor before returning to the compressor to begin the cycle again. consulab.com info@consulab.com 25 91-EV-2000 SA-5 - LEVEL I — Heating the Cabin SA-5 - LEVEL I — Heating the Cabin Instructor Notes Teaching Suggestions Part 1 – Tracing the Flow to Heat the Cabin • Just as in SA-4, encourage students to both color code and label each refrigerant state on the schematic. Writing out terms like high pressure vapor, low pressure liquid, etc., supports vocabulary retention and prepares them for interpreting unlabeled industry diagrams. • Emphasize how the flow has changed from Mode 1 to Mode 2 as the core new concept here. Ask students to verbal- ly explain how EEVs are used and how the role of the external heat exchanger can change. • Have students compare their SA5 diagram with their SA4 diagram to see the same components performing the op- posite roles. This reinforces heat pump theory. Part 2 – Collecting Pressure & Temperature Data • If only one EV-2000 unit is available, call up different students to perform and call out each reading while the rest of the class records the data. • Encourage students to add their readings directly onto the schematic, reinforcing spatial understanding of pressure and temperature at each location. • Remind them that they’ve taken line temperatures in earlier assignments for Mode 1, and they should refer back to that data to help interpret superheat, subcooling, and heat pump operation in Mode 2. Practical Applications • Students learn to compare line temperatures (compressor discharge, condenser outlet, suction line) with cabin out- let air temperature. This skill directly applies to diagnosing customer concerns such as: - “My heat is lukewarm at idle.” - “The car heats but not enough in cold weather.” • By knowing which line should be hot or cold in Mode 2, students can identify a stuck reversing valve, an under- charged system (low discharge temp), a restricted condenser or metering valve, or a blend door fault (normal line temps but poor cabin outlet temp). • This lab teaches students how to identify which EEV should be active and what temperatures should be present up- stream and downstream. This becomes crucial in real repairs for systems that heat poorly because the wrong EEV is stuck open, vehicles that fail to defrost because the chiller or cabin evaporator is being fed accidentally, or heat pump systems that oscillate between heating and cooling due to incorrect metering. The ability to compare clamp on line temps to expected refrigerant states helps technicians quickly pinpoint faulty metering valves, one of the most common failures in reversible systems. consulab.com info@consulab.com 26 91-EV-2000 SA-5 - LEVEL I — Heating the Cabin Answers Objective: Identify reversing valve function and record outlet air temperature during heat pump heating. Material Required: EV-2000, power supply, Blank Schematic with ID diagram, clamp-on thermometer, digital probe thermometer Part 1 – Trace the Flow to Heat the Cabin Use the Blank Schematic with ID diagram to complete the following: 1. Draw arrows showing the refrigerant path starting from the compressor Label and color where the refrigerant is: - RED: high pressure vapor - YELLOW: high pressure liquid - DARK BLUE: low pressure liquid - LIGHT BLUE: low pressure vapor 2. Identify in which component the refrigerant “absorbs heat” as the evaporator 3. Identify in which component the refrigerant “releases heat” as the condenser 4. Label where subcooling occurs 5. Label where superheat occurs 6. Put an X on any components not used during this mode. 7. Check your work with your instructor before moving on. Part 2 – Collect Pressure and Temperature Data 8. Turn on the EV-2000 and select Mode 2 – Cabin Heat: Heat Pump. Allow the system to run for 1-2 minutes to reach stable operating conditions. With the system running, record the pressures: - High side pressure (PSI): 175 - Low side pressure (PSI): 20 9. Based on the diagram from Part 1, identify: - Which component is being supplied by high pressure vapor from the compressor. Cabin condenser - Which component is returning low pressure vapor to the compressor. External Heat Exchanger 10. Clamp the pipe thermometer on the high side line leaving the compressor. - Compressor discharge temperature: 123° F / 51° C consulab.com info@consulab.com 27 91-EV-2000 SA-5 - LEVEL I — Heating the Cabin 11. Clamp the thermometer on the liquid line leaving the cabin condenser. - Condenser outlet (liquid) temperature: 112° F / 44° C 12. Clamp the thermometer on the suction line entering the compressor. - Suction line temperature: 92°F / 33° C 13. Record the cabin outlet air temperature with the digital probe thermometer. - Cabin outlet temperature: 97° F / 36° C - Ambient room temperature: 70° F / 21° C 14. Add the pressure and temperature readings written above to the diagram from Part 1. Part 3 – Interpret the Measurements 15. Compare the data by answering yes or no to the following statements: - Does the compressor discharge line exhibit a higher sensible heat level (feel hotter) than the condenser outlet? Yes - Does the suction line exhibit lower sensible heat (feel cooler) than the cabin condenser outlet? Yes - Is the high side pressure noticeably higher than the low side? Yes, much higher. - Does this match what a heat pump should be doing in heating mode? Yes 16. In one sentence, explain what the pressure and temperature readings say about whether the heat pump cycle is functioning correctly in Mode 2. The higher pressure and temperature on the high side and lower pressure and temperature on the low side show that the heat pump is operating correctly and delivering sensible heat to the cabin in Mode 2. 17. Identify active expansion valves (EEV): - Which expansion valve is active in this Mode? EV1 - Which expansion valve was active in Mode 1? EV2 - Why can’t multiple expansion valves meter refrigerant at the same time? Use the terms: evaporator, low pressure liquid, chiller, external heat exchanger, cabin condenser, and EEV. There are three EEVs, and only one should operate in this mode because EV1 directs low pressure liquid refriger- ant to the external heat exchanger, where the refrigerant absorbs heat from outside and brings it into the system. High pressure vapor then leaves the compressor and flows through the cabin condenser, where it releases heat to warm the cabin. If EV3 opened, low pressure liquid would be sent to the chiller, which is not used in this mode. If EV2 opened, refrigerant would be sent to the wrong location and cabin heating would drop. Only EV1 should operate in Mode 2 for proper heating. consulab.com info@consulab.com 28 91-EV-2000 SA-6 - LEVEL II — Electronic Expansion Valves SA-6 - LEVEL II — Electronic Expansion Valves Instructor Notes Teaching Suggestions • When reviewing the TXV vs. EEV comparison, emphasize that the big difference is control strategy, not refrigeration theory. This helps prevent students from thinking EEVs “do something different” thermodynamically. • Before students take any measurements, ask them to predict what they expect to see before and after EV2 in Mode 1. This reinforces cause and effect reasoning instead of passive data collection. • Encourage students to use the clamp on thermometer as a pressure indicator, reminding them that temperature change across an EEV reflects a pressure drop and change in saturation temperature. • When switching from Mode 1 (EV2) to Mode 2 (EV1), emphasize that although the component being fed changes, the measured behavior across the EEV should look very similar. This reinforces that EV1 and EV2 perform the same function in different modes. • Do not explain EV3 ahead of time. Let students deduce its purpose based on location and prior observations. This mirrors real diagnostic thinking and builds confidence. • If discussing system architecture, keep the focus on layout and function, not brand names. Some OEMs use cen- tralized routing with integrated manifolds, while others use distributed EEVs throughout the circuit. In all cases, the refrigeration principles remain the same: EEVs control pressure, pressure determines saturation temperature, and superheat confirms correct operation. • There are two filters on the product that are used to protect the three EEVs in case particles are present and could potentially block one or more EEVs. Practical Applications • Students learn that EEVs always create a pressure drop, allowing them to quickly determine expected refrigerant states upstream and downstream of a valve during diagnostics. • By measuring temperatures before and after EV1 and EV2, students practice identifying a valve stuck too far open (low superheat, higher evaporator pressure) or stuck too far closed (high superheat, low evaporator pressure) • Understanding that EV3 feeds the battery chiller helps students connect HVAC operation to battery thermal man- agement, a critical skill in modern EV service. consulab.com info@consulab.com 29 91-EV-2000 SA-6 - LEVEL II — Electronic Expansion Valves Answers Objective: Describe how electronic expansion valves create a pressure drop to control refrigerant flow. Material Required: EV-2000, power supply, clamp-on thermometer Part 1 – What is an Electronic Expansion Valve? An electronic expansion valve (EEV) is a metering device that controls how much liquid refrigerant enters an evaporator in order to maintain a target superheat at the evaporator outlet. Like all expansion devices, its primary job is to create a pressure drop, which lowers the refrigerant’s saturation temperature and allows it to absorb heat. Unlike mechanical thermal expansion valves, an EEV is controlled electronically by a system controller using pressure and temperature sensor inputs. Instead of reacting passively, the controller com- mands valve position to maintain the desired refrigerant condition at the evaporator outlet. Mechanical Expansion Valves Electronic Expansion Valves (EEV) • Uses a sensing bulb, diaphragm, and spring • Reacts mechanically to temperature changes • Adjusts flow slowly • Best suited for steady operating conditions • Uses an electric motor (often a stepper motor) • Controlled by software using pressure and tempera- ture inputs • Adjusts flow quickly and precisely • Well suited for variable load and multimode systems Important: Although the control method is different, the refrigeration principles are the same. EEV Position and Refrigerant Behavior Changing EEV position directly affects evaporator pressure, saturation temperature, and superheat: • EEV opens → more refrigerant flow → higher evaporator pressure → higher saturation temperature → lower su- perheat • EEV closes → less refrigerant flow → lower evaporator pressure → lower saturation temperature → higher super- heat This cause and effect relationship is the same whether the evaporator is cooling air, a liquid loop, or a battery system. When to Use Superheat and Subcooling Use superheat and subcooling when evaluating refrigerant metering and refrigerant condition, especially around an expansion device: • to verify that an expansion valve is feeding correctly, • to determine whether an evaporator is starved or flooded, • to confirm proper refrigerant condition before or after a component, • and to verify refrigerant side repairs. consulab.com info@consulab.com 30 91-EV-2000 SA-6 - LEVEL II — Electronic Expansion Valves Superheat tells us what the refrigerant looks like after the expansion device, at the evaporator outlet. Subcooling tells us what the refrigerant looks like before the expansion device, in the liquid line leaving the condenser. If the expansion valve is doing its job, superheat and subcooling fall within a normal range. If they do not, these values indicate how the system is being fed incorrectly, not just that performance is poor. Part 2 – EEV Operation 1. Regardless of which component it feeds, what is the primary function of any electronic expansion valve in a refriger- ation system? A. To increase refrigerant temperature before it enters the evaporator B. To route refrigerant to different heat exchangers C. To create a pressure drop that controls refrigerant pressure and saturation temperature D. To compress refrigerant vapor before it enters the condenser 2. Complete the information about EV2 feeding the cabin evaporator in Mode 1. This information will be used to evalu- ate superheat at the evaporator outlet. A. The refrigerant is low / high pressure liquid / vapor before it enters EV2. B. The refrigerant becomes low / high pressure liquid / vapor after EV2. C. The temperature of the refrigerant before EV2 is 81° F / 27° C D. The temperature of the refrigerant after EV2 is 61° F / 16° C 3. If EV2 opens further while feeding the cabin evaporator, what happens to evaporator pressure and saturation tem- perature, and how does this affect superheat at the evaporator outlet? If EV2 opens further while feeding the cabin evaporator, the evaporator pressure increases because more refriger- ant is allowed to flow into the evaporator. As pressure increases, the saturation temperature also increases. With more refrigerant entering the evaporator, the refrigerant is more fully used, which reduces superheat. This shows how EV2 controls pressure, temperature, and superheat by adjusting its opening. 4. Complete the information about EV1 feeding a different evaporator in Mode 2. Use this information to compare superheat control to Question 2. A. The refrigerant is low / high pressure liquid / vapor before it enters EV1. B. The refrigerant becomes low / high pressure liquid / vapor after EV1. C. The temperature of the refrigerant before EV2 is 100° F / 38° C D. The temperature of the refrigerant after EV2 is 68° F / 20° C 5. How is the function of EV1 in Mode 2 like EV2 in Mode 1, even though it feeds a different component? EV1 and EV2 both perform the same function by creating a pressure drop to control evaporator pressure and main- tain proper superheat, even though they feed different components. 6. Locate EV3. Based on its location, predict when EV3 will be used and what refrigerant measurement would be most useful to confirm it is feeding correctly. EV3 will be used when the system needs to chill the glycol loop to cool the battery. Superheat at the evaporator or chiller outlet would be the most useful measurement to confirm that EV3 is feeding correctly. consulab.com info@consulab.com 31 91-EV-2000 SA-7 - LEVEL II — Cabin Heat and Defrost SA-7 - LEVEL II — Cabin Heat and Defrost Instructor Notes Teaching Suggestions • Reinforce early that Mode 3 is still a heating mode, but with additional system behavior to support defrost; the cab- in never stops being heated. • Emphasize that components must be identified by function, not by their name on the schematic. What matters is whether a component is absorbing or releasing heat in this mode. • Encourage careful color coding of refrigerant states, as this visually reveals that multiple components are absorbing heat at the same time. • Ask students to explain aloud where heat is being absorbed and where it is being released before confirming their diagrams. • Remind students that pressure indicates phase change, while temperature change indicates heat transfer; both are needed to interpret Mode 3 correctly. • If students are confused by seeing one cabin component absorb heat while another releases heat, guide them to- ward the idea of dehumidify then reheat, rather than correcting them directly. • Use superheat and subcooling calculations as evidence, not as the goal; students should use these values to justify system behavior. Practical Application and Diagnostics • This assignment mirrors real world windshield defrost operation, where warm, dry air is required rather than maxi- mum heat alone. • Students learn why a system can absorb heat from cabin air and outside air while still delivering warm air to the windshield. • Understanding Mode 3 helps prevent misdiagnosis of customer concerns such as “the heat works but defrost is weak” or “the system feels like it cools before heating.” • The lab builds confidence in diagnosing systems where multiple heat exchangers are active simultaneously. • Emphasize that defrost is a control strategy, not a separate system, and that modern vehicles achieve it by manag- ing heat sources rather than shutting heating off. consulab.com info@consulab.com 32 91-EV-2000 SA-7 - LEVEL II — Cabin Heat and Defrost Answers Objective: Explain the difference between heating mode and defrost mode by identifying refrigerant states, pressure, and temperature changes. Material Required: EV-2000, power supply, Blank Schematic with ID diagram, clamp-on thermometer Part 1 – Trace the Flow of Heat and Defrost Use the Blank Schematic with ID diagram to complete the following: 1. Draw arrows showing the refrigerant path starting from the compressor Label and color where the refrigerant is: - RED: high pressure vapor - YELLOW: high pressure liquid - DARK BLUE: low pressure liquid - LIGHT BLUE: low pressure vapor 2. Identify in which component(s) the refrigerant “absorbs heat” as the evaporator 3. Identify in which component the refrigerant “releases heat” as the condenser 4. Label where subcooling occurs 5. Label where superheat occurs 6. Put an X on any components not used during this mode. Check your work with your instructor before moving on. Part 2 – Collect and Calculate Data Using manifold gauges and clampon temperature probes, collect pressure and temperature data at the locations listed below while the EV-2000 is operating in Mode 3. Component Inlet Outlet Cabin Evaporator 66° F / 19° C 68° F / 21° C Cabin Condenser 113° F / 45° C 104° F / 40° C External Heat Exchanger 54° F / 12° C 67° F / 20° C Pressure Readings Suction Line Discharge Line Pressure 20 PSI 180 PSI Pressure Converted Temperature 22° F / -5.5° C 124° F / 51° C consulab.com info@consulab.com 33 91-EV-2000 SA-7 - LEVEL II — Cabin Heat and Defrost Using the temperatures and pressure converted temperatures, calculate superheat and subcooling: Amount of Superheat = Actual Suction Line Temp – Saturation Temp Amount of Subcooling = Saturation Temp – Actual Liquid Line Temp Superheat after Evaporator 68° F - 22° F = 46° F Subcooling after Cabin Condenser 124° F - 104° F = 20° F Superheat after Heat Exchanger 67° F – 22° F = 45° F EV-2000 Superheat Specifications Superheat What It Means System Condition 28 ° C) Too High Evaporator starved; undercharge, restriction, airflow problem, or metering issue EV-2000 Subcooling Specifications Subcooling What It Means System Condition 40 ° F (> 22 ° C) Too High Overcharge, restricted airflow, or condenser flooding Part 3 – Determining Heat vs. Defrost Use your data and schematic to answer the following: 1. At the cabin evaporator, the refrigerant gains heat as it passes through the component. 2. At the cabin condenser, the refrigerant loses heat as it passes through the component. 3. At the external heat exchanger, does the refrigerant absorb heat or release heat? How does this support the system’s operation during Mode 3? At the external heat exchanger, the refrigerant absorbs heat. This helps the system by bringing in fresh dry air from the outside to aid in heating and defrosting. consulab.com info@consulab.com 34 91-EV-2000 SA-7 - LEVEL II — Cabin Heat and Defrost 4. Compare the behavior of the refrigerant in the cabin evaporator and the cabin condenser. In Mode 3, which component is providing cabin heating, and which component is supporting defrost operation? Explain your reasoning. In Mode 3, the cabin condenser is providing cabin heating because it releases heat, and the cabin evaporator is sup- porting defrost because it absorbs heat and helps remove moisture from the air. 5. Using your low side and high side pressure readings and the refrigerant states shown on your diagram, how can the system heat the cabin while still absorbing heat from outside in Mode 3? A. The cabin evaporator raises refrigerant pressure so it can release heat at the condenser. B. The compressor increases refrigerant pressure so heat absorbed at low pressure can be released at high pres- sure in the cabin. C. The external heat exchanger switches roles and becomes a condenser during defrost. D. Heat is stored in the refrigerant during cooling and released later during defrost. consulab.com info@consulab.com 35 91-EV-2000 SA-8 - LEVEL I — Heating the Cabin Without Refrigerant SA-8 - LEVEL I — Heating the Cabin Without Refrigerant Instructor Notes Teaching Suggestions 1. Emphasize early that Mode 4 does not use refrigerant to heat the cabin. This lesson is intentionally about separating heat creation from heat movement. 2. When introducing the term Positive Temperature Coefficient, slow students down and focus on the material behav- ior, not just the acronym. The key idea is that resistance increases as temperature increases. 3. Reinforce that the PTC heater is self regulating by physics, not by software or thermostats. This is a new concept for many students and worth repeating. 4. Encourage careful probe placement on glycol lines. Remind students that clamp on thermometers measure pipe temperature, which reflects fluid temperature only when contact is solid. Use the metal portions of the lines for best measurements. Practical Application and Diagnostics • This lesson mirrors real EV behavior during cold starts, when heat pumps may be slow or ineffective and immediate heat is needed. • Understanding PTC operation helps students diagnose customer concerns such as: - “The heat works right away, even when it’s very cold.” - “The car heats fine but uses a lot of energy in winter.” • The self regulating nature of PTC heaters explains why they are commonly used for heated seats, battery heating, and cabin preconditioning. • Being able to identify heat added to glycol versus heat released at the heater core prepares students for later les- sons involving combined PTC + heat pump modes. • Emphasize that technicians must know which system is responsible for heating before diagnosing faults; misidentify- ing PTC operation can lead to incorrect conclusions about refrigerant charge or compressor performance. consulab.com info@consulab.com 36 91-EV-2000 SA-8 - LEVEL I — Heating the Cabin Without Refrigerant Answers Objective: Explain how a Positive Temperature Coefficient (PTC) heater works and why it is used for cabin heating in electric vehicles. Material Required: EV-2000, power supply, Mode 4 = Cabin Heat : PTC + Glycol Radiator schematic, clamp-on ther- mometer Part 1 – What is a PTC Heater? PTC stands for Positive Temperature Coefficient. A PTC heater is an electric heating device made from special ceramic materials whose electrical resistance increases as temperature rises. When electrical current is first applied, the heater has low resistance and produces heat quickly. As the heater warms up, its resistance increases, which automatically reduces the current flow and limits the heat output. The “positive” in Positive Temperature Coefficient means that tem- perature and resistance rise together, and this makes a PTC heater self regulating, meaning it can safely control its own temperature without overheating. In electric vehicles, the PTC heater is used to heat the glycol (coolant) loop, not the refrigerant. Unlike a heat pump which moves heat from one place to another, the PTC heater converts electrical energy directly into heat, which is transferred to the circulating glycol. That warm glycol is then pumped to the batteries to warm them up, or pumped through a heat- er core to heat the cabin air. This method is especially important during cold starts, because a PTC heater can produce heat immediately, without waiting for refrigerant pressures or temperatures to stabilize. PTC heating is also commonly used for heated seats and can work in tandem with the HVAC heat pump system during extremely cold conditions to supplement cabin or battery heating. Part 2 – Measuring Glycol Temperature Change Review the Mode 4 schematic and identify which components are active and which are not used during this mode. Lo- cate the glycol circuit and identify the following four temperature measurement points: • Glycol entering the PTC heater • Glycol leaving the PTC heater • Glycol entering the heater core • Glycol leaving the heater core Using clampon thermometer probes, measure and record the glycol temperature at each location. Component Inlet Outlet PTC Heater 73° F / 23° C 81° F / 26° C Heater Core 77° F / 25° C 73° F / 23° C consulab.com info@consulab.com 37 91-EV-2000 SA-8 - LEVEL I — Heating the Cabin Without Refrigerant Part 3 – Check for Understanding 1. Fill in the Blank. PTC stands for Positive Temperature Coefficient, meaning the heater’s electrical resistance increases as temperature increases. 2. Why is a PTC heater especially useful during cold startup conditions? A PTC heater is useful during cold startup because it can make heat right away using electricity, instead of waiting for the refrigerant system to warm up. 3. Based on your temperature measurements, where and how much heat is being added to the system and where and how much heat is being released to the cabin? Answer using complete sentences. About eight degrees of heat is being added to the system at the PTC heater because the glycol temperature increas- es as it passes through it. About four degrees of heat is released to the cabin at the heater core because the glycol temperature decreases as it flows through the heater core and warms the cabin air. 4. What are two major differences between cabin heating using a PTC heater (Mode 4) and cabin heating using a heat pump (Mode 2). One difference is that a PTC heater creates heat directly using electricity, while a heat pump moves heat from one place to another using refrigerant. Another difference is that the PTC heater heats glycol to warm the cabin, while the heat pump uses refrigerant pressure and phase change to provide heat. consulab.com info@consulab.com 38 91-EV-2000 Section 1 - Cabin Components Assessment Section 1 - Cabin Components Assessment Match the component to its function: Component Function 1. Evaporator A. Releases heat 2. Condenser B. Absorbs heat 3. PTC Heater C. Transfers heat between glycol and refrigerant 4. Chiller D. Electrically creates heat 1. B, 2. A, 3. D, 4. C Select the correct answer. 5. What type of refrigerant can a compressor pump? A. Liquid only B. Vapor only C. Liquid and vapor D. Saturated liquid 6. Why does discharge temperature increase after compression? A. Heat is added by a heater B. Refrigerant condenses C. Compression increases pressure and sensible heat D. The evaporator adds heat 7. Where does superheat occur? A. Evaporator outlet B. Liquid line C. Condenser outlet D. Expansion valve inlet 8. Why is subcooling important? A. Prevents icing B. Ensures liquid enters the expansion valve C. Raises compressor temperature D. Increases airflow consulab.com info@consulab.com 39 91-EV-2000 Section 1 - Cabin Components Assessment 9. Blocking condenser airflow will most likely cause: A. Lower high side pressure B. Increased subcooling C. Increased high side pressure D. Reduced superheat 10. The primary job of any EEV is to: A. Create a pressure drop B. Compress vapor C. Route heat D. Store refrigerant 11. Why is the cabin evaporator active during defrost? A. To cool the cabin B. To stop heating C. To raise pressure D. To remove moisture from air 12. A PTC heater creates heat using: A. Refrigerant phase change B. Compressor pressure C. Ambient air D. Electrical resistance consulab.com info@consulab.com 40 91-EV-2000 SA-9 - LEVEL II — Effects of a Restricted Expansion Valve SA-9 - LEVEL II — Effects of a Restricted Expansion Valve Instructor Notes Teaching Suggestions • This assignment builds directly on SA-5 (Heating Mode), SA-6 (EEVs), and SA-7 (Heating + Defrost). Encourage students to refer to those diagrams and notes as needed, especially when identifying EV1 and the role of the external heat exchanger. • Before students begin, insert Fault 3: Restricted EV1 so that all measurements reflect the faulted condition during data collection. • Guide students to think in terms of cause and effect, not memorization: - Restricted flow → lower evaporator pressure - Lower pressure → lower saturation temperature - Less refrigerant boiling → elevated superheat • To speed up the assignment, you may choose to provide students with the normal/expected Mode 2 values in Part 2 instead of requiring them to reference earlier assignments or recreate baseline data. • When reviewing calculations, remind students that superheat and subcooling are diagnostic tools, not just math exercises. Ask them what each value proves about refrigerant flow. • Faults remain stored in memory. For example, if Fault 1 is activated in Mode 1, it will affect system operation. If you switch to Mode 2, where Fault 1 does not apply, the F1 LED will flash, but the fault will not affect the system. If you switch back to Mode 1 or another Mode that supports that Fault, Fault 1 becomes active again. Faults remain active whenever the selected mode supports that fault. Practical Applications and Diagnostics • Students learn how to distinguish a metering restriction from other faults such as low refrigerant charge, airflow issues, or compressor problems. • Understanding that high subcooling with low low side pressure points to a restriction helps prevent unnecessary component replacement. • The ability to diagnose EV1 restriction in heating mode prepares students for customer concerns such as: - “The heat is weak even though pressures look normal.” - “The system runs but doesn’t warm up well in cold weather.” Optional Extension Repeat the same activity in Mode 3: Cabin Heat + Defrost: Heat Pump and have students compare how the restricted EV1 affects defrost performance versus normal heating. This reinforces that the diagnostic principles remain the same even as system operation becomes more complex. consulab.com info@consulab.com 41 91-EV-2000 SA-9 - LEVEL II — Effects of a Restricted Expansion Valve Answers Objective: Diagnose a mechanically restricted expansion valve by comparing normal and faulted system data and inter- preting changes in low side pressure, superheat, and subcooling during cabin heating operation. Material Required: EV-2000, power supply, Mode 2 diagram, clamp-on thermometer Part 1 – Reviewing Expansion Valve Function Use your diagrams and the EV-2000 in Modes 2 and 3 to answer the following review questions. 1. What is the primary function of an electronic expansion valve (EEV) in a refrigeration system? A. To create a pressure drop so refrigerant can absorb heat B. To compress refrigerant vapor C. To store excess refrigerant D. To transfer heat between loops 2. Fill in the Blank. During Mode 2 : Cabin Heat and Mode 3 : Cabin Heat + Defrost, the active expansion valve that feeds the external heat exchanger is EV1. 3. In Mode 2 and Mode 3, what role does the external heat exchanger play in the system? A. It releases heat to the cabin air B. It transfers heat between glycol and refrigerant C. It stores excess refrigerant D. It absorbs heat and acts as the evaporator 4. When refrigerant passes through EV1, a pressure drop occurs. However, on the EV-2000, pressure is not measured directly on both sides of EV1. So, even though pressure cannot be measured directly before and after EV1, techni- cians can still diagnose a restriction. Which two calculated values can be used instead? (Circle two.) - Suction pressure - Discharge pressure - Superheat - Subcooling Review the answers with an instructor before moving on. consulab.com info@consulab.com 42 91-EV-2000 SA-9 - LEVEL II — Effects of a Restricted Expansion Valve Part 2 – Collecting Mode 2: EV1 Data Compare the normal operating values of Mode 2 to the values measured while EV1 is restricted. For each measurement, circle whether the actual value is greater than, less than, or similar to the normal value, and use the trends to help diag- nose the restriction. Measurement Location Normal Value Measured Value Data Trends Value under normal operating conditions Value while EV1 is restricted Circle Actual v. Normal Observations EV1 Inlet Temperature 104° F / 40° C 110° F / 43° C Measured value is greater than / less than / similar to normal value EV1 Outlet Temperature 86° F / 30° C 72° F / 22° C greater than / less than / similar to External Heat Changer Outlet 79° F / 26° C 86° F / 30° C greater than / less than / similar to Cabin Condenser Inlet Temperature 115° F / 46° C 104° F / 40° C greater than / less than / similar to Cabin Condenser Outlet Temperature 106° F / 41° C 95° F / 35° C greater than / less than / similar to Low-side Pressure 30 PSI 18 PSI greater than / less than / similar toLow-side Pressure Converted Temperature 35° F / 1.4° C 19° F / -7° C High-side Pressure 200 PSI 225 PSI greater than / less than / similar toHigh-side Pressure converted Temperature 133° F / 56° C 138° F / 59° C Part 3 – Calculating Superheat and Subcooling Using the pressure and temperature data collected above, calculate superheat and subcooling for both normal oper- ation and restricted EV1 operation. Compare the results to determine how the restriction affects refrigerant flow and evaporator performance. EV-2000 Superheat Specifications Superheat What It Means System Condition 28 ° C) Too High Evaporator starved; undercharge, restriction, airflow problem, or metering issue consulab.com info@consulab.com 43 91-EV-2000 SA-9 - LEVEL II — Effects of a Restricted Expansion Valve EV-2000 Subcooling Specifications Subcooling What It Means System Condition 40 ° F (> 22 ° C) Too High Overcharge, restricted airflow, or condenser flooding Superheat = Actual Suction Line Temp – Saturation Temp Subcooling = Saturation Temp – Actual Liquid Line Temp Superheat and Subcooling Under Normal Operating Conditions Use the Normal Value column of your table to calculate superheat and subcooling for Mode 2. Superheat = 79° F – 35° F = 44° F Subcooling = 133° F - 106° F = 27° F Superheat and Subcooling While EV1 is Restricted Use the Measured Value column of your table to calculate superheat and subcooling for Mode 2. Superheat = 86° F - 19° F = 67° F Subcooling = 133° F – 95° F = 38° F Part 3 – Results of Restricted Expansion Valve 5. When EV1 is restricted, the lowside pressure drops compared to normal operation. What does this most directly indicate? A. Too much refrigerant is entering the evaporator B. Refrigerant flow into the evaporator is restricted C. The compressor is over compressing refrigerant D. The condenser is rejecting too much heat 6. The high side pressure remains the same while EV1 is restricted. What does this help rule out? A. Restricted airflow across the condenser B. A mechanically restricted expansion valve C. A refrigerant undercharge D. Normal heating operation 7. Which combination of measurements most strongly confirms a mechanically restricted EV1? A. High low side pressure and low superheat B. Normal pressures and normal superheat C. Low low side pressure, high superheat, increased subcooling D. High high side pressure and low subcooling consulab.com info@consulab.com 44 91-EV-2000 SA-9 - LEVEL II — Effects of a Restricted Expansion Valve 8. Compare the subcooling values between normal and restricted operation. Why would subcooling increase when refrigerant flow through EV1 is restricted? Subcooling is higher when EV1 is restricted because refrigerant is backing up in the condenser instead of flowing normally through the system. The reduced flow causes the liquid refrigerant to cool more below its saturation tem- perature, which increases subcooling and indicates a restriction rather than a normal operating condition. consulab.com info@consulab.com 45 91-EV-2000 SA-10 - LEVEL III — Restricted vs. Blocked Expansion Valves SA-10 - LEVEL III — Restricted vs. Blocked Expansion Valves Instructor Notes Teaching Suggestions • This assignment extends SA9 by moving from limited refrigerant flow to no meaningful refrigerant flow. Emphasize that students are now diagnosing a system that has stopped doing the thing the math assumes. • Students should compare behavior, not memorize symptoms. The goal is recognizing when diagnostic strategies must change as system operation collapses. • Insert Fault 4: EV1 Stuck Shut before students begin data collection. • Run the system in Mode 2: Cabin Heat for all measurements. • If students do not have quick access to their SA9 results, provide the SA9 data set to keep the focus on comparison rather than recollection. • When EV1 is fully blocked in this activity, the EV-2000 low side pressure will rapidly drop and the system will trip at approximately 6 PSI due to an internal low pressure safety limit. This shutdown is expected and intentional and is designed to protect the compressor when refrigerant flow to the evaporator stops. If the system trips before students can record all measurements, this reinforces the learning objective: a blocked expansion valve prevents refrigerant flow, leading to unsafe operating conditions that require system protection. • At extremely low suction pressures, calculated superheat continues to increase numerically even though meaningful evaporation has stopped. Practical Applications • This activity mirrors real world scenarios where a blocked expansion valve can resemble a low charge condition unless system behavior is carefully analyzed. • Students practice differentiating: - Restricted vs. blocked metering devices - Flow related faults vs. charge or airflow issues • Emphasize that recognizing collapsed suction pressure with minimal heat absorption helps prevent unnecessary component replacement. Optional Extension • Repeat the comparison in Mode 3: Cabin Heat + Defrost. • Have students evaluate whether the same diagnostic principles apply as system complexity increases. • Reinforce that while operating modes change, fault signatures and reasoning remain consistent. consulab.com info@consulab.com 46 91-EV-2000 SA-10 - LEVEL III — Restricted vs. Blocked Expansion Valves Answers Objective: Explain how a stuck-shut EEV prevents proper refrigerant evaporation and describe the impact on thermal system behavior. Material Required: EV-2000, power supply, Mode 2 diagram, clamp-on thermometer Part 1 – Collect Mode 2 Data Use the data collected in SA-9 to complete the first column, then put the EV-2000 in Mode 2 and collect the data for the second column. Measurement Location SA-9 Value Measured Value While EV1 is restricted While EV1 is blocked EV1 Inlet Temperature 110° F / 43° C 104° F / 40° C EV1 Outlet Temperature 72° F / 22° C 77° F / 25° C External Heat Changer Outlet 86° F / 30° C 82° F / 28° C Cabin Condenser Outlet Temperature 104° F / 40° C 97° F / 36° C Low-side Pressure 18 PSI 6 PSI Low-side Pressure Converted Temperature 19 F / -7° C 0.0° F / -18° C High-side Pressure 225 PSI 250 PSI High-side Pressure converted Temperature 138° F / 59° C 145° F / 63° C Part 2 – Compare Restricted vs. Blocked Expansion Valve For each measurement below, circle whether the blocked EV1 value is greater than, less than, or similar to the re- stricted EV1 value. 1. Low side pressure is greater than / less than / similar to the restricted condition. 2. Low side saturation temperature is greater than / less than / similar to the restricted condition. 3. EV1 outlet temperature is greater than / less than / similar to the restricted condition. 4. External heat exchanger outlet temperature is greater than / less than / similar to the restricted condition. 5. High side pressure is greater than / less than / similar to the restricted condition. consulab.com info@consulab.com 47 91-EV-2000 SA-10 - LEVEL III — Restricted vs. Blocked Expansion Valves Assume the external heat exchanger outlet temperature represents the suction line temperature. Use the formula below to calculate superheat. Superheat = Actual Suction Line Temperature − Saturation Temperature 6. Restricted EV1 (SA-9): Superheat = 86° F – 19° F = 67° F 7. Blocked EV1 (SA-10): Superheat = 82° F – 0.0° F = 82° F Assume the cabin condenser outlet temperature represents the liquid line temperature. Use the formula below to cal- culate subcooling. Subcooling = Saturation Temperature − Actual Liquid Line Temperature 8. Restricted EV1 (SA-9): Subcooling = 138°F - 104°F = 34°F 9. Blocked EV1 (SA-10): Subcooling = 145 °F − 97 °F = 48 °F EV-2000 Superheat Specifications Superheat What It Means System Condition 28 ° C) Too High Evaporator starved; undercharge, restriction, airflow problem, or metering issue EV-2000 Subcooling Specifications Subcooling What It Means System Condition 40 ° F (> 22 ° C) Too High Overcharge, restricted airflow, or condenser flooding Answer the following analysis questions using the data and calculation above as evidence. 10. When EV1 is blocked, the extremely low low side pressure most directly indicates: A. Refrigerant is not entering the external heat exchanger B. Increased refrigerant flow into the evaporator C. Refrigerant boiling more efficiently D. Excessive airflow across the heat exchanger consulab.com info@consulab.com 48 91-EV-2000 SA-10 - LEVEL III — Restricted vs. Blocked Expansion Valves 11. Which observation best distinguishes a blocked expansion valve from a restricted one? A. Elevated subcooling B. Normal high side pressure C. Extremely low suction pressure with minimal evaporator heat absorption D. Slightly reduced cabin heating performance 12. Complete the statement below using appropriate technical terms: A restricted expansion valve allows limited refrigerant flow, resulting in reduced evaporator pressure but continued evaporation. A blocked expansion valve prevents refrigerant flow, causing suction pressure to drop and evaporator heat absorption to stop. 13. In SA-9, refrigerant was still able to evaporate even though EV1 was restricted. Explain why evaporation largely stops when EV1 is blocked. When EV1 was restricted, it still allowed a small amount of refrigerant to enter the evaporator, making evapora- tion possible even though system performance was reduced. When EV1 is blocked, refrigerant cannot flow into the evaporator. Without refrigerant entering and expanding, the evaporator cannot absorb heat or undergo a phase change. As a result, suction pressure drops dramatically and evaporation largely stops because there is no refriger- ant available to boil. 14. When EV1 was restricted superheat helped confirm the restriction. In a blocked expansion valve, superheat be- comes less reliable. Why? A. Pressure sensors are inaccurate at low pressures B. Superheat calculations assume active evaporation C. Subcooling becomes more important than superheat D. The compressor stops compressing refrigerant consulab.com info@consulab.com 49 91-EV-2000 SA-11 - LEVEL III — Diagnosing the Evaporator SA-11 - LEVEL III — Diagnosing the Evaporator Instructor Notes Teaching Suggestions • Insert Fault 9 Iced Cabin Evaporator • Allow flexibility in temperature measurement locations. The goal is not identical data, but whether students can defend why a measurement supports their diagnosis. • In Mode 3, encourage students to compare behavior across modes rather than expecting “new” symptoms. The learning target is recognizing a consistent fault signature across different operating strategies. • When operating in Mode 3 with Fault 9 applied, there is little to no impact on system pressures. The only way to diagnose the problem is to use a thermometer and confirm that there is no fan operation at the cabin evaporator. • If students do not have quick access to prior EEV assignment data, you may provide an EEV comparison data set so time is spent on reasoning, not data recovery. • During this activity, the EV-2000 low side pressure may drop to approximately 6 PSI, at which point the system will trip due to an internal low pressure safety limit. This behavior is expected and is designed to protect the compres- sor during conditions where evaporator heat absorption is severely reduced. If shutdown occurs before all data is recorded, it reinforces the diagnostic goal of this activity: evaporator icing can drive suction pressure to unsafe levels even when the refrigerant circuit and controls are otherwise functional. Practical Applications and Diagnostics • This activity mirrors real world concerns such as: - “The A/C runs but barely blows.” - “Cooling is weak and defrost doesn’t clear the windshield.” • Students learn that airflow and heat transfer failures can closely resemble refrigerant side problems unless visual and functional checks are performed. • Comparing Mode 1 and Mode 3 demonstrates that icing and airflow faults affect both cooling and defrost, whereas EEV metering faults primarily affect refrigerant behavior. • The comparison matrix trains students to separate refrigerant movement problems from heat exchange problems, reducing misdiagnosis and unnecessary part replacement. consulab.com info@consulab.com 50 91-EV-2000 SA-11 - LEVEL III — Diagnosing the Evaporator Answers Objective: Analyze temperature and pressure data to distinguish evaporator icing from EEV-related underflow or system undercharge. Material Required: EV-2000, power supply, Mode 1 & Mode 3 diagrams, clamp-on thermometer Part 1 – Collect Mode 1: Cabin Cool Data Place the EV-2000 in Mode 1: Cabin Cool. Your job is to determine what is limiting system performance based on evi- dence. Perform a visual inspection by circling the symptoms observed below: 1. Cabin evaporator airflow feels: Strong / Moderate / Weak / Almost none 2. Cabin evaporator vent air temperature feels: Cold / Cool / Neutral / Warm / None 3. Listen/observe: Does the system sound like it is running normally? Yes / No 4. What is your initial diagnosis from your visual inspection? Based on these observations, system performance appears to be limited at or near the evaporator, either due to a problem with heat transfer at the evaporator or an issue affecting the refrigerant path feeding the evaporator. Based on your visual inspection diagnosis select four important temperature measurements to support your claim and record them here: NOTE: Choice of measurements may vary. Measurement Value 1. Evaporator Inlet 39° F / 4° C 2. Evaporator Outlet 37° F / 3° C 3. EV2 Inlet 106° F / 41° C 4. Compressor Outlet 136° F / 58° C Low-side Pressure 6 PSI High-side Pressure 120 PSI Calculate superheat and subcooling in the space below. 5. Superheat = Suction line temp − Lowside saturation temp Superheat = 37° F - 0° F = 37° F 6. Subcooling = Highside saturation temp − Liquid line temp Subcooling = 97° F - 106° F = -9° F consulab.com info@consulab.com 51 91-EV-2000 SA-11 - LEVEL III — Diagnosing the Evaporator 7. Based on the evidence collected so far, the system is most likely limited by: ☐ Refrigerant movement Heat exchange with air ☐ Electrical control ☐ Refrigerant quantity Justification: The system is running and pressures indicate refrigerant movement, but weak vent airflow and poor cooling show that heat is not being effectively transferred between the evaporator and the cabin air. EV-2000 Superheat Specifications Superheat What It Means System Condition 28 ° C) Too High Evaporator starved; undercharge, restriction, airflow problem, or metering issue EV-2000 Subcooling Specifications Subcooling What It Means System Condition 40 ° F (> 22 ° C) Too High Overcharge, restricted airflow, or condenser flooding Part 2 – Compare to Mode 3: Cabin Heat + Defrost Data Switch to Mode 3: Cabin Heat + Defrost and complete the following comparisons: 8. Compared to Mode 1, vent airflow in Mode 3 feels: ☐ Stronger About the same ☐ Weaker 9. Low side pressure in Mode 3 is: Higher than Mode 1 ☐ Similar to Mode 1 ☐ Lower than Mode 1 consulab.com info@consulab.com 52 91-EV-2000 SA-11 - LEVEL III — Diagnosing the Evaporator 10. Cabin evaporator outlet temperature in Mode 3 is: 70° F / 21° C ☐ Lower than expected ☐ Near saturation temperature Higher than expected 11. Calculate superheat for Mode 3. Compared to Mode 1, Mode 3 superheat is: 70° F - 22° F = 48° F ☐ Lower ☐ Similar Higher 12. With this fault active in Mode 3, defrost performance is most likely to: ☐ Improve normally over time Be weak or inconsistent Fail to clear the windshield effectively ☐ Appear unaffected Part 3 – Compare Against an Expansion Valve Fault This section helps distinguish airflow or icing concerns from an EEV restriction or stuck condition by comparing system patterns. Complete the matrix using the results of today’s inspection in the first column and previous EEV assignments or the instructor-provided EEV data in the second column. Evidence/Symptom Mode 1 & 3 Observations EEV Metering Fault Data Vent airflow is noticeably reduced YES / NO / UNKNOWN YES / NO / UNKNOWN Visual frost/ice present YES / NO / UNKNOWN YES / NO / UNKNOWN Low-side pressure lower than expected YES / NO / UNKNOWN YES / NO / UNKNOWN Refrigerant leaving evap is hotter than expected (high superheat) YES / NO / UNKNOWN YES / NO / UNKNOWN Mode 3 defrost performance is weakened YES / NO / UNKNOWN YES / NO / UNKNOWN 13. Which single observation best separates airflow/icing from an EEV metering fault? A. Low side pressure is lower than normal B. High side pressure is lower than normal C. Vent airflow drops noticeably D. Superheat increases consulab.com info@consulab.com 53 91-EV-2000 SA-11 - LEVEL III — Diagnosing the Evaporator 14. Which two observations together most strongly indicate that the system limitation is not primarily refrigerant-flow related? Weak vent airflow ☐ Normal system sound and response ☐ Elevated calculated superheat ☐ Low side pressure trending downward Visible frost or ice on the evaporator Justify your choice below. These belong together because ice on the evaporator blocks airflow, which reduces cooling even if refrigerant is still moving through the system. 15. Rank the following types of evidence from most important to least important for diagnosing this fault: 3 Pressure readings 4 Superheat calculation 2 Visual inspection of evaporator 1 Vent airflow observation Then, explain why your top choice deserves the most weight. Vent airflow is the most important because it immediately shows that the air is not moving properly, which points to a heat transfer problem rather than a refrigerant flow problem. 16. Based on all observations and measurements, what is the fault? The cabin evaporator is iced and airflow across it is restricted. consulab.com info@consulab.com 54 91-EV-2000 SA-12 - LEVEL III — Diagnosing a Cabin Performance Concern SA-12 - LEVEL III — Diagnosing a Cabin Performance Concern Instructor Notes Teaching Suggestions • Set Fault 12, Restricted Airflow Cabin Evaporator, before starting this assignment. • Reinforce the sequence observe → hypothesize → test → decide → confirm. Students should not begin with pres- sure readings before completing the visual and functional inspection. • When reviewing Part 1, guide students to identify patterns across modes, especially observations that remain con- sistent between Mode 1 and Mode 3. • Allow flexibility in diagnostic procedures in Part 2. Different step orders and measurement choices are acceptable as long as students can explain why each step matters. • When operating in Mode 3 with Fault 12 applied, there is little to no impact on system pressures. The only way to diagnose the problem is to use a thermometer and confirm that there is no fan operation at the cabin evaporator. • In Part 3, stress the importance of contradicting evidence. A strong diagnosis explains not only why one cause fits, but why others are less likely. • Use the final confirmation step (restoring normal operation) to reinforce that system recovery is valid diagnostic evidence, not just a “fix.” Practical Applications • This activity mirrors real world HVAC concerns such as: - “The system runs, but the air feels weak.” - “Cooling and defrost don’t work well.” • Students learn that airflow and heat transfer limitations can closely resemble refrigerant undercharge or metering faults unless airflow is verified. • Comparing behavior across Modes 1–3 helps students recognize that: - Refrigerant metering faults are often mode dependent - Airflow/heat exchange faults tend to be mode independent and affect both cooling and defrost • The supports contradict framework trains students to avoid part swapping logic and instead rely on evidence con- sistency, reducing misdiagnosis in real service situations. consulab.com info@consulab.com 55 91-EV-2000 SA-12 - LEVEL III — Diagnosing a Cabin Performance Concern Answers Objective: Design and apply a diagnostic procedure to determine what is limiting cabin performance by collecting evi- dence, evaluating competing fault hypotheses, and justifying a final diagnosis. Material Required: EV-2000, power supply, Mode 1, Mode 2, & Mode 3 diagrams, clamp-on thermometer Part 1 – Perform a Visual Inspection Review the customer concern. Before collecting pressure or temperature data, cycle through modes 1-3 and perform a visual and functional inspection by recording information in the table below. Customer Concern: “The climate system turns on and seems to be working, but the cabin doesn’t perform the way it should. Sometimes the air doesn’t blow very strongly, and other times the temperature doesn’t change much even though the system is running. In certain situations, the windshield takes a long time to clear. The problem seems to hap- pen in more than one climate setting, but no warning lights are present.” Mode-by-Mode Observation Table Observation Mode 1 : Cabin Cooling Mode 2 : Cabin Heating Mode 3 : Heat + Defrost Cabin airflow feels: Normal / Reduced / Poor Normal / Reduced / Poor Normal / Reduced / Poor Temperature at the vent feels: Cool, but not cold, less intensity Warm Warm, but weak, no defrost System sounds like it is operating normally? Yes / No / Not sure Yes / No / Not sure Yes / No / Not sure Any visible changes to note? Decreasing low pressure until it trips No visible changes Subtle decrease in pressure to normal Cabin performance in this mode feels: Normal / Reduced / Poor Normal / Reduced / Poor Normal / Reduced / Poor 1. Which observation appears consistently across more than one mode? Which modes? Cabin airflow feels reduced in Mode 1 and Mode 3. 2. Which observation changes the most when switching modes? The vent temperature changes the most. Heating works better in Mode 2, but cooling in Mode 1 and defrost in Mode 3 are weak. consulab.com info@consulab.com 56 91-EV-2000 SA-12 - LEVEL III — Diagnosing a Cabin Performance Concern 3. Based on the inspection, which area of the system might be limiting performance? ☐ Refrigerant movement ☐ Electrical control Heat exchange with air ☐ Not enough information yet 4. What result would you expect to see if this diagnosis is correct? If this diagnosis is correct, I would expect pressure and temperature measurements to show that refrigerant is mov- ing but not transferring heat well, like low pressure on both sides and poor cooling even though the system is on. Part 2 – Design and Test a Diagnostic Procedure Review your answers from Part 1. Identify what part of the system you believe may be limiting performance. Write your procedure below to test and diagnose your theory in 4–6 steps total. A good procedure usually includes: • an airflow or functional check • a refrigerant side check • a comparison across modes • a way to calculate superheat and/or subcooling Step 1: Check cabin vent airflow and temperature in all modes Observation/Measurement: Will vary, but air flow is reduced and not as cold in Mode 1 & 3 Step 2: Check low-side and high-side pressure in Mode 1 & Mode 3 Observation/Measurement: Will vary, both low and high-side pressure drops in Mode 1, & drops slightly in Mode 3 Step 3: Measure temperature near evaporator inlet and outlet in Mode 1 Observation/Measurement: Will vary, but temperature difference across evap will be smaller than expected Step 4: Use pressure and temperature to calculate superheat Observation/Measurement: Will vary, superheat should be higher than expected. Step 5: Compare results across Modes 1-3 Observation/Measurement: Will vary, same airflow and cooling problems appear in Mode 1 and Mode 3 Step 6: Observation/Measurement: EV-2000 Superheat Specifications Superheat What It Means System Condition 28 ° C) Too High Evaporator starved; undercharge, restriction, airflow problem, or metering issue consulab.com info@consulab.com 57 91-EV-2000 SA-12 - LEVEL III — Diagnosing a Cabin Performance Concern EV-2000 Subcooling Specifications Subcooling What It Means System Condition 40 ° F (> 22 ° C) Too High Overcharge, restricted airflow, or condenser flooding Part 3 – Make a Diagnosis Consider the following possible causes of the cabin performance issue, for each diagnosis below, list one piece of evi- dence that supports it or one piece of evidence that contradicts it. 5. Refrigerant metering problem (EEV): Less likely because airflow is weak in more than one mode, not just one, and both pressures drop instead of backing up. 6. System undercharge: Low pressure could suggest low refrigerant, but heating still works better in Mode 2, so refrig- erant is likely present. 7. Heatexchange limitation: Weak airflow and poor cooling and defrost in multiple modes support a problem with heat transfer to the air. 8. Based on all observations and measurements, what do you believe is most likely limiting cabin performance? ☐ Refrigerant movement ☐ Refrigerant quantity Heat exchange with air ☐ Electrical control Justify your choice and recommend a service or repair solution in the space below. The system runs and pressures change, but airflow is reduced and cooling and defrost are weak. This suggests refrigerant is moving but not absorbing enough heat. The repair would be to find and fix what is restricting airflow across the cabin evaporator. 9. After normal operation was restored by the instructor, what one change most strongly confirmed your diagnosis? Airflow increased and cooling improved, confirming the problem was related to heat exchange, not refrigerant flow. consulab.com info@consulab.com 58 91-EV-2000 Section 2 – Cabin Flow Assessment Section 2 – Cabin Flow Assessment 1. In heating mode, the external heat exchanger mainly acts as a: A. Condenser B. Evaporator C. Compressor D. Receiver 2. Superheat is best described as: A. Liquid temperature below its condensing temperature B. Vapor temperature above its boiling (saturation) temperature at that pressure C. The difference between high side and low side pressure D. The temperature difference between cabin air and outside air 3. Which symptom is the strongest clue of an airflow/heat transfer problem at the cabin heat exchanger? A. Low low side pressure B. High superheat C. Weak or uneven airflow at the vents D. Low high side pressure 4. A metering restriction (partly blocked valve) most commonly creates which pattern? A. High low side pressure and low superheat B. Low low side pressure, higher superheat, and higher subcooling C. Normal low side pressure and normal subcooling D. High low side pressure and high subcooling 5. The main job of a metering device (expansion valve/orifice) is to: A. Raise refrigerant pressure B. Remove moisture from the air C. Store refrigerant D. Create a pressure drop so refrigerant can boil and absorb heat 6. A fully blocked (stuck shut) metering device is most likely to cause: A. Strong cooling and low superheat B. Extremely low suction pressure and little to no evaporation C. High low side pressure due to flooding D. Higher airflow at the vents consulab.com info@consulab.com 59 91-EV-2000 Section 2 – Cabin Flow Assessment 7. Restricted airflow across the evaporator reduces performance mainly because: A. It blocks refrigerant tubes directly B. It reduces heat transfer into the refrigerant C. It increases refrigerant charge D. It increases compressor displacement 8. Which situation can look like an undercharge at first glance if you only look at pressures? A. Restricted airflow across the evaporator B. A stuck open metering device C. A high refrigerant charge D. A working defrost system 9. A key early sign of evaporator icing is often: A. Airflow gets stronger and stronger B. Airflow gradually drops off and performance gets worse C. High side pressure instantly spikes D. Vent temperature instantly becomes hot 10. You measure low suction pressure and high superheat. Airflow at the vents feels normal. Which diagnosis is most likely? A. Airflow restriction B. Cabin air filter clogging C. Blower motor failure D. Metering restriction (refrigerant underflow) consulab.com info@consulab.com 60 91-EV-2000 SA-13 - LEVEL I — Introduction to Battery Cooling SA-13 - LEVEL I — Introduction to Battery Cooling Instructor Notes Teaching Suggestions • Emphasize that this assignment is about understanding system purpose, not troubleshooting or fault diagnosis. • Reinforce that battery cooling and cabin cooling have different goals: battery cooling prioritizes stability and longevi- ty, while cabin cooling prioritizes comfort and speed. • Encourage students to focus on temperature trends, not exact values. The key learning point is where the glycol warms up and where it cools down. • Keep discussion at the system level, not component level. Detailed chiller operation is intentionally deferred to later assignments. Practical Applications • This activity mirrors real world EV design decisions, where manufacturers use the simplest and most efficient cooling method that meets battery needs. • Students learn that batteries are not cooled the same way as cabins because rapid temperature changes can re- duce battery life. • The assignment reinforces that coolant loops are commonly used for batteries to provide even temperature control and electrical isolation. • This assignment prepares students for later battery cooling scenarios and faults involving: - High ambient temperatures - Combined cabin and battery thermal management consulab.com info@consulab.com 61 91-EV-2000 SA-13 - LEVEL I — Introduction to Battery Cooling Answers Objective: Describe when glycol-based battery cooling is used instead of HVAC refrigerant cooling based on system design and operating conditions. Material Required: EV-2000, power supply, Mode 5 diagram, clamp-on thermometer Part 1 – EV Battery Cooling Electric vehicle batteries need steady and controlled cooling, not fast or aggressive temperature changes. HVAC refrig- erant systems are designed to change temperature quickly for passenger comfort, but rapid temperature swings can shorten battery life. A glycol loop cools the battery slowly and evenly, protecting the battery while maintaining stable operation. Using an external radiator with glycol provides gentle heat removal, while refrigerant based chiller cooling is much more powerful and can be excessive when battery heat levels are moderate. The battery and the cabin often need cooling at different times, so separating their cooling systems improves efficien- cy. The battery may need cooling during charging, hard driving, or long trips even when the cabin does not. Using the HVAC chiller every time would waste energy and unnecessarily run the compressor. Glycol cooling uses only a pump and airflow through a radiator, making it more energy efficient for light to moderate heat loads. Refrigerant cooling is still important, but it is best reserved for high load or extreme temperature conditions, acting as backup rather than the default battery cooling method. Part 2 – Observe Glycol Temperatures Place the EV-2000 in Mode 5: Battery Cool: Glycol Radiator. Allow the system around three minutes to stabilize before recording temperatures. Measure and record the glycol temperatures below. Measurement Location Temperature Glycol inlet to battery 81° F / 27° C Glycol outlet from battery 90° F / 32° C Glycol inlet to radiator 90° F / 32° C Glycol outlet from radiator 79° F / 26° C Part 3 – Analyze the Cooling System Use the reading from Part 1 and your observations from Part 2 to answer the questions below. 1. Fill in the blanks. Glycol based battery cooling is preferred when the battery heat load is light/moderate. 2. Fill in the blanks. Refrigerant based battery cooling is typically reserved for high-load or extreme temperature operating conditions. consulab.com info@consulab.com 62 91-EV-2000 SA-13 - LEVEL I — Introduction to Battery Cooling 3. Fill in the blanks. A glycol cooling loop removes heat from the battery using a pump and an external radiator, with- out running the compressor. 4. Based on your measurements, is the glycol: ☐ Absorbing heat from the battery ☐ Releasing heat at the radiator Doing both 5. Explain two benefits of using glycol based battery cooling instead of the HVAC chiller and describe how separating cabin cooling from battery cooling improves system operation. Using glycol cooling instead of the HVAC chiller reduces energy use and prevents unnecessary wear on the com- pressor. Keeping battery cooling separate from cabin cooling allows each system to work independently and more efficiently, depending on what the vehicle needs at the time. 6. Using the glycol temperature readings, explain how heat moves through the glycol loop to cool the battery in Mode 5. The answer should describe where the glycol absorbs heat and where it releases heat. The glycol enters the battery at 81°F (27°C) and leaves the battery warmer at 90°F (32°C), which shows that it is ab- sorbing heat from the battery. The warm glycol then flows into the radiator at 90°F (32°C) and leaves cooler at 79°F (26°C), showing that the radiator is releasing heat to the outside air. This cycle repeats as the cooled glycol returns to the battery to remove more heat and keep the battery at a safe temperature. consulab.com info@consulab.com 63 91-EV-2000 SA-14 - LEVEL II — Battery Cooling with HVAC SA-14 - LEVEL II — Battery Cooling with HVAC Instructor Notes Teaching Suggestions • In Mode 6, the external heat exchanger fans are modulated based on low-side pressure in order to stabilize system pressures. This is an excellent teaching point to demonstrate how the system reacts according to the heat absorbed by the glycol coming from the high voltage battery. • Encourage students to both color code and label refrigerant states on the schematic. Writing out terms such as high pressure vapor or low pressure liquid reinforces vocabulary and helps students interpret industry schematics that are not color coded. • Emphasize that the chiller does not replace the evaporator or condenser but instead acts as a heat transfer inter- face between two separate loops. Students should be able to point to where heat changes loops, not just where it changes state. • When students mark unused components, use this as a checkpoint to confirm they understand which parts of the HVAC system are active and which are isolated during battery cooling with the chiller. • Before allowing students to take temperatures, require them to predict which inlet/outlet pairs matter most. This helps prevent random probing and builds intentional measurement habits. Accept different predicted measurement points as long as students justify them using heat flow logic rather than memorized answers. • If only one EV-2000 is available, have students rotate roles: one measures, one reads values aloud, one records on the schematic, and one records in data table. This keeps the entire group engaged. • Encourage students to write temperature values directly on their schematic near the corresponding components to reinforce spatial understanding. Practical Applications • This activity reflects real EV thermal management strategies, where battery heat is often removed indirectly rather than by blowing air across the battery. • Students learn that the chiller allows manufacturers to: - Keep battery cooling independent from cabin comfort - Use refrigerant cooling only when needed - Transfer heat efficiently between loops without mixing fluids consulab.com info@consulab.com 64 91-EV-2000 SA-14 - LEVEL II — Battery Cooling with HVAC Answers Objective: Explain the function of a chiller as the interface between refrigerant and glycol loops in EV thermal management. Material Required: EV-2000, power supply, Blank Schematic with ID diagram, clamp-on thermometer Part 1 – Trace the Flow to Cool the Batteries Use the Blank Schematic with ID diagram to complete the following: 1. Draw arrows showing the refrigerant path starting from the compressor Label and color where the refrigerant is: - RED: high pressure vapor - YELLOW: high pressure liquid - DARK BLUE: low pressure liquid - LIGHT BLUE: low pressure vapor 2. Label where the refrigerant “absorbs heat” 3. Label where the refrigerant “releases heat” 4. Label where subcooling occurs 5. Label where superheat occurs 6. Draw arrows showing the glycol path starting from the glycol pump Label and color where glycol is: - GREEN: cold - PURPLE: warm 7. Put an X on any components not used during this mode. Check your work with your instructor before moving on. 8. Which glycol temperature measurement points will be best to show that heat is being removed from the battery? The best glycol measurement points are the glycol inlet to the battery and the glycol outlet from the battery. If the glycol is removing heat, the temperature leaving the battery should be higher than the temperature entering it, show- ing that heat was absorbed from the battery. consulab.com info@consulab.com 65 91-EV-2000 SA-14 - LEVEL II — Battery Cooling with HVAC 9. Which refrigerant temperature measurement points will be best to show that it is properly cooling the glycol? The best refrigerant measurement points are the refrigerant inlet to the chiller and the refrigerant outlet from the chiller. If the refrigerant is cooling the glycol, the refrigerant should absorb heat in the chiller, causing a temperature change that shows heat transfer is taking place. Part 2 – Collect Temperature Data Place the EV-2000 in Mode 6: Batt Cool: HVAC and allow the system to stabilize for 2–3 minutes before collecting tem- perature below. Glycol Temperature Measurements Inlet to Battery / Outlet from Chiller 72° F / 22° C Outlet from Battery 80° F / 27° C Inlet to Chiller 79° F / 26° C Battery Light Color Blue 10. Compared to the inlet, the glycol leaving the battery is: Warmer ☐ Cooler ☐ About the same 11. Compared to the inlet, the glycol leaving the chiller is: ☐ Warmer Cooler ☐ About the same Refrigerant Temperature Measurements Inlet to Chiller 46° F / 8° C Outlet from Chiller 63° F / 17° C 12. As refrigerant passes through the chiller, it is primarily: Absorbing heat ☐ Releasing heat ☐ Not changing temperature consulab.com info@consulab.com 66 91-EV-2000 SA-14 - LEVEL II — Battery Cooling with HVAC Part 3 – Evaluate System Functionality Use your schematic work from Part 1 and the temperature data collected in Part 2 to answer the following questions. 13. Based on the glycol and refrigerant temperature changes in this mode, where is the battery’s heat ultimately released? A. Into the cabin air through the vents B. Into the refrigerant loop only, where it remains stored C. To the outside air through the external heat exchanger D. Back into the battery once the glycol cools down 14. Based on the glycol temperature measurements, explain how you know heat is being removed from the battery. The answer should reference specific inlet and outlet temperatures. The glycol enters the battery at 72°F (22°C) and leaves the battery warmer at 80°F (27°C). This increase in tem- perature shows that the glycol is absorbing heat from the battery as it flows through it, which means heat is being removed from the battery. 15. In this mode, which loop is acting as the heat source and which loop is acting as the heat sink? Justify the choice with data. The battery/glycol loop is acting as the heat source because the glycol temperature increases after leaving the battery (72°F to 80°F). The refrigerant loop is acting as the heat sink because it absorbs heat in the chiller, shown by the refrigerant temperature rising from 46°F (8°C) at the inlet to 62°F (17°C) at the outlet. 16. Explain why the chiller is described as an “interface” between the refrigerant loop and the glycol loop.The answer should include what each loop does and how heat moves between them. The chiller is called an interface because it allows heat to move from the glycol loop to the refrigerant loop without the two fluids mixing. The glycol brings heat from the battery to the chiller, and the refrigerant absorbs that heat inside the chiller and carries it away to be released outside the vehicle. consulab.com info@consulab.com 67 91-EV-2000 SA-15 - LEVEL I — Introduction to Battery Heating SA-15 - LEVEL I — Introduction to Battery Heating Instructor Notes Teaching Suggestions • Reinforce that Mode 7 is a glycol only battery heating mode; the refrigerant system is not used. • Briefly refresh the PTC heater function: it converts electrical energy into heat and is self regulating, reducing output as temperature rises. • Use the battery indicator color change (blue → yellow) as confirmation, not the primary evidence of heating. • You may provide students with the Mode 7 diagram, or have them use the blank schematic and label: • Green for cooler glycol • Purple for warmer glycol • Allow students to write measured temperatures directly on their diagrams instead of the data table to reinforce spatial understanding of heat flow. • When comparing Mode 5 and Mode 7, stress that the same glycol loop is used, but the direction of heat flow reverses. • Reinforce the role change: - Mode 5: battery is the heat source - Mode 7: battery is the heat sink Practical Application This mirrors real EV operation in cold conditions, where the battery must be warmed for performance and charging even when the cabin may not need heat. consulab.com info@consulab.com 68 91-EV-2000 SA-15 - LEVEL I — Introduction to Battery Heating Answers Objective: Diagram the coolant and airflow paths for battery heating and compare it to battery cooling. Material Required: EV-2000, power supply, Mode 7 diagram, Mode 5 diagram, clamp-on thermometer Part 1 – Observe Glycol Temperatures Place the EV-2000 in Mode 7: Battery Heat: PTC + Glycol. Allow the system about three minutes to stabilize, then record the glycol temperatures below. Measurement Location Temperature Glycol inlet to battery 80° F / 27° C Glycol outlet from battery 72° F / 22° C Glycol inlet to PTC heater 74° F / 23° C Glycol outlet from PTC heater 88° F / 31° C Battery Light Color Blue to Yellow 1. During this battery heating mode, which component is acting as the main heat source for the battery? A. The battery itself B. The radiator C. The PTC heater D. The heater core 2. How does a PTC heater differ from a traditional resistive heater? A. It produces constant heat regardless of temperature B. It requires external control to prevent overheating C. It only works when refrigerant is present D. It automatically reduces heat output as temperature rises Part 2 – Compare Battery Cooling and Heating Use the Mode 5 and Mode 7 diagrams and your temperature data of both to answer the questions below. 3. In Mode 5 (Battery Cooling), identify: - Where heat is absorbed: HV battery - Where heat is released: external radiator consulab.com info@consulab.com 69 91-EV-2000 SA-15 - LEVEL I — Introduction to Battery Heating 4. In Mode 7 (Battery Heating), identify: - Where heat is absorbed: PTC heater - Where heat is released: HV battery 5. Compare Mode 5 and Mode 7: How does the battery’s role in the heat transfer process change between the two modes? In Mode 5 (battery cooling), the battery acts as the heat source because heat is absorbed from the battery by the glycol. In Mode 7 (battery heating), the battery acts as the heat sink because heat is delivered to the battery by the warm glycol coming from the PTC heater. 6. Why is it useful for the vehicle to use the same glycol loop for both battery cooling and battery heating instead of having two separate systems? Using the same glycol loop for both heating and cooling reduces system complexity and allows the vehicle to con- trol battery temperature more efficiently. The system can simply change where heat is added or removed, instead of needing separate loops, pumps, and components for heating and cooling. 7. The glycol temperature increases leaving the PTC heater, but the battery temperature does not rise as expected when in the battery heating mode. Technician A says that the problem could be a glycol flow issue, because heat cannot reach the battery if the glycol is not circulating properly. Technician B says that the problem must be in the refrigerant system, because the battery is not warming up. Which technician is correct? A. Technician A only B. Technician B only C. Both Technician A and Technician B D. Neither Technician A nor Technician B consulab.com info@consulab.com 70 91-EV-2000 SA-16 - LEVEL II — Glycol Heating System Performance Analysis SA-16 - LEVEL II — Glycol Heating System Performance Analysis Instructor Notes Teaching Suggestions • Activate Fault 13 PTC Heater Does Not Engage before class; this fault affects Mode 4 and Mode 7 only. • Reinforce that if Mode 5 behaves normally, students should rule out the glycol pump and flow as the primary issue. • Guide students toward the intended deduction path: - Mode 5 proves glycol flow and heat transfer are working. - Modes 4 and 7 both rely on the PTC heater to add heat to the glycol. - Therefore, if PTC inlet ≈ outlet temperature in both modes, heat is not being added. • Allow students to record temperatures directly on the Mode 4/5/7 diagrams instead of only using tables; this sup- ports visual reasoning. Practical Applications • This activity mirrors real EV concerns where both cabin heat and battery warmup are poor, especially in cold weather. • Students learn how technicians use a known good operating mode to isolate a fault rather than guessing or replac- ing parts. • By requiring students to propose a repair and verification step, this lab models complete diagnostic workflow, not just fault identification. consulab.com info@consulab.com 71 91-EV-2000 SA-16 - LEVEL II — Glycol Heating System Performance Analysis Answers Objective: Use temperature and flow evidence across multiple glycol modes to determine why heating performance is reduced and recommend a repair. Material Required: EV-2000, power supply, Mode 4, Mode 5, and Mode 7 diagrams, clamp-on thermometer Part 1 – Customer Intake Review the customer concern below and gather the required materials to diagnose the issue. Customer Concern: “In cold conditions, the battery takes a long time to warm up and the cabin heat is weak. No warn- ing lights are present.” 1. Which glycol-only Modes are going to be the most relevant to this diagnosis? Select all that apply: Mode 4: Cabin Heat: PTC + Glycol Radiator ☐ Mode 5: Batt Cool: Glycol Radiator Mode 7: Batt Heat: PTC + Glycol Part 2 – Collect Data to Diagnose Cycle through Modes 4, 5, and 7 to collect evidence before diagnosing. Record your observations in the space below. Mode 4: Cabin Heat: PTC + Glycol Radiator Glycol Inlet to PTC Temperature 75° F / 24° C Glycol Outlet from PTC Temperature 75° F / 24° C Heater Core Inlet Temperature 77° F / 25° C Heater Core Outlet Temperature 75° F/ 24° C Cabin Heat Performance Normal / Weak / Poor Pump Operational? Yes / No / Unsure PTC Operational? Yes / No / Unsure consulab.com info@consulab.com 72 91-EV-2000 SA-16 - LEVEL II — Glycol Heating System Performance Analysis Mode 5: Batt Cool: Glycol Radiator Glycol Inlet to Battery Temperature 81° F / 27° C Glycol Outlet from Battery Temperature 90° F / 32° C Battery Indicator Light Blue Radiator Operational? Yes / No / Unsure Pump Operational? Yes / No / Unsure Mode 7: Batt Heat: PTC + Glycol Glycol Inlet to Battery Temperature 79° F / 26° C Glycol Outlet from Battery Temperature 79° F / 26° C Glycol Inlet to PTC Temperature 79° F / 26° C Glycol Outlet from PTC Temperature 79° F / 26° C Battery Indicator Light Blue Part 3 – Diagnosis and Suggested Service 2. What evidence shows the glycol loop is functioning normally in Mode 5? In Mode 5, the glycol temperature increases from 81°F (27°C) at the battery inlet to 90°F (32°C) at the outlet, which shows heat is being absorbed from the battery. This confirms the glycol is circulating properly and transferring heat, so the pump and loop are functioning normally. 3. In Modes 4 and 7, did glycol temperature increase across the PTC heater? What does that indicate? No, the glycol temperature does not increase across the PTC heater in either Mode 4 or Mode 7. The inlet and outlet temperatures are about the same, which indicates the PTC heater is not adding heat to the glycol when heating is requested. 4. If glycol flow appears normal in Mode 5 but heating is weak in both Modes 4 and 7, what component/function is most likely limiting performance? A. Glycol pump/flow B. PTC heat addition C. Refrigerant system D. Airflow/blower 5. Explain why this is a heating issue and not a cooling issue, using your mode comparisons. Cooling works normally in Mode 5, which shows the glycol loop can circulate and change temperature. Heating is weak in both Mode 4 and Mode 7, which means the issue only appears when heat needs to be added. This shows the problem is with heating, not cooling. consulab.com info@consulab.com 73 91-EV-2000 SA-16 - LEVEL II — Glycol Heating System Performance Analysis 6. What is your diagnosis and recommended repair? What measurement would you recheck after repair to confirm the fix? The diagnosis is that the PTC heater is not engaging when requested. The recommended repair is to repair or replace the PTC heater or its electrical control circuit. After the repair, I would recheck the glycol inlet and outlet temperatures at the PTC heater to confirm that the outlet temperature rises above the inlet. consulab.com info@consulab.com 74 91-EV-2000 SA-17 - LEVEL II — Heat Transfer from the Battery to the Cabin SA-17 - LEVEL II — Heat Transfer from the Battery to the Cabin Instructor Notes Teaching Suggestions • In Mode 8, the cabin condenser fans are modulated based on low-side pressure in order to stabilize system pres- sures. • Emphasize that Mode 8 uses both the glycol loop and the refrigerant loop at the same time, and that the chiller is the interface between the two. • Clarify that superheat begins after the refrigerant fully vaporizes in the chiller, before it reaches the accumulator. • For differentiation, Part 2 may be completed verbally with the instructor or as a recorded video explanation as long as the correct order and vocabulary are used. Practical Applications • Students see how EV thermal systems prioritize and reuse available heat instead of generating new heat whenever possible to save range and maintain performance. • Understanding this combined mode prepares students to diagnose conditions where heat is available but not deliv- ered effectively, such as chiller, refrigerant, or airflow related issues Optional Extension As an extension have students compare Mode 8 to Mode 6 (Battery Cooling with HVAC) to see how the same chiller is used in two different ways: • Mode 6: removing heat from the battery • Mode 8: transferring battery heat to the cabin consulab.com info@consulab.com 75 91-EV-2000 SA-17 - LEVEL II — Heat Transfer from the Battery to the Cabin Answers Objective: Analyze simultaneous heat pump operation for cabin heating and battery cooling and interpret sensor data. Material Required: EV-2000, power supply, Blank Schematic with ID diagram, clamp-on thermometer Part 1 – Trace the Flow to Cool the Batteries Use the Blank Schematic with ID diagram to complete the following: 1. Draw arrows showing the refrigerant path starting from the compressor Label and color where the refrigerant is: - RED: high pressure vapor - YELLOW: high pressure liquid - DARK BLUE: low pressure liquid - LIGHT BLUE: low pressure vapor 2. Label where the refrigerant “absorbs heat” 3. Label where the refrigerant “releases heat” 4. Label where subcooling occurs 5. Label where superheat occurs 6. Draw arrows showing the glycol path starting from the glycol pump Label and color where glycol is: - GREEN: cold - PURPLE: warm 7. Put an X on any components not used during this mode. Concept Check 8. Mode 8 uses heat from the battery to warm the cabin. ☐ This mode places a high thermal load on the heat pump This mode places a low thermal load on the heat pump Explain your choice: In Mode 8, heat from the battery is reused to warm the cabin. Since the system is already using heat that exists, the heat pump does not have to work very hard to make new heat. Because of that, the heat pump experiences a lower thermal load. Check your work with your instructor before moving on. consulab.com info@consulab.com 76 91-EV-2000 SA-17 - LEVEL II — Heat Transfer from the Battery to the Cabin Part 2 – How the Battery Heats the Cabin Create a step-by-step procedure that explains how heat from the battery is used to heat the cabin in Mode 8. The se- quence must: • Start at the battery • End with warm air entering the cabin • Be written in numbered steps (1, 2, 3, …) • Use the following vocabulary: glycol, chiller, refrigerant, low pressure vapor, compressor, high pressure vapor, cabin condenser, superheat, glycol pump, saturation temperature 1. Heat is absorbed by the glycol as it flows through the battery, warming the glycol. 2. The warm glycol is pumped to the chiller by the glycol pump. 3. Inside the chiller, the refrigerant absorbs heat from the glycol and boils, leaving the chiller as a low pressure vapor. 4. After leaving the chiller, the refrigerant contains superheat, meaning it is fully vaporized and warmer than its satura- tion temperature. 5. The low pressure vapor flows through the accumulator to the compressor. 6. The compressor raises the pressure and temperature, turning the refrigerant into a high pressure vapor. 7. The hot refrigerant enters the cabin condenser, where it releases heat. 8. Air blown across the cabin condenser absorbs this heat, and warm air enters the cabin. consulab.com info@consulab.com 77 91-EV-2000 SA-18 - LEVEL III — Abnormal Heat Transfer SA-18 - LEVEL III — Abnormal Heat Transfer Instructor Notes Teaching Suggestions • Set Fault 10 Iced External Heat Exchanger before students begin • Clamp on thermometers and superheat calculations may be used if students need confirmation, but the emphasis is on pressure trends, performance, and system response. Expected Diagnostic Patterns • Load-Dependent Severity - Issue becomes severe when the system must reject large amounts of heat (Modes 1 and 6) - Issue is muted or partially hidden when alternate heat sources or paths exist (Mode 3) - Indicates a heat rejection / heat exchange limitation, not a control or valve command issue. • Pressure Behavior Varies by Mode - Some modes show rapid high side pressure increase - Other modes show both pressures dropping - Behavior changes depending on which heat exchanger is active - Rules out: Low refrigerant charge, Single EEV stuck open or closed, Compressor underperformance • Progressive Performance Loss - Heating or cooling performance drops before hard limits are reached - Indicates gradual loss of heat transfer, not an on/off failure - Encourages thinking in terms of surface effectiveness, not failed components. Key Mode Signals • Mode 1: Rapid loss of heat rejection • Mode 2: Evaporator side starved of usable heat • Mode 3: Alternate heat source masks the issue • Mode 6: Heat rejection failure under high load Practical Application • Mirrors real EV concerns that appear only under high thermal demand (fast charging, heavy cabin cooling). • Reinforces that technicians diagnose patterns under load, not single readings. consulab.com info@consulab.com 78 91-EV-2000 SA-18 - LEVEL III — Abnormal Heat Transfer Answers Objective: Collect system measurements to recognize when heat exchange performance is compromised during normal operation. Material Required: EV-2000, power supply, Mode 1-8 diagrams Part 1 – Customer Intake Review the customer concern below and gather the required materials to diagnose the issue. Customer Concern: “Sometimes the cabin doesn’t cool very well and the system shuts itself down after a short time. In colder weather, the cabin heat feels weak. During fast charging, the vehicle occasionally limits power or cooling perfor- mance.” 1. Based on the customer’s concerns, select all the vehicle functions that may be affected: Cabin cooling performance Cabin heating performance Battery cooling during high load or fast charging System protection or power limiting behavior ☐ Defrost or windshield clearing performance ☐ Refrigerant system pressure control ☐ Glycol loop heat transfer 2. Based on the vehicle functions you selected above, choose the operating modes you would investigate first. Mode 1 — Cabin Cool: Heat Pump Mode 2 — Cabin Heat: Heat Pump Mode 3 — Cabin Heat + Defrost: Heat Pump ☐ Mode 4 — Cabin Heat: PTC + Glycol ☐ Mode 5 — Battery Cool: Glycol Radiator Mode 6 — Battery Cool: HVAC ☐ Mode 7 — Battery Heat: PTC +Glycol NOTE: Acceptable if student explains combined thermal demand ☐ Mode 8 — Cabin Heat & Battery Cool: HVAC consulab.com info@consulab.com 79 91-EV-2000 SA-18 - LEVEL III — Abnormal Heat Transfer Part 2 – Mode-by-Mode Observation For each operating mode you selected in Part 1, operate the system and record your observations below. Use relative terms (rises quickly, slowly increases, stable, decreases) to identify patterns. Mode High-side Pressure Trend Low-side Pressure Trend System Performance Protective Response Mode 1 Ramps up and trips Small increase Cold air felt, but per- formance reduced High Pressure Limit Mode 2 Small decrease low side drops less heat felt Low Pressure Limit Mode 3 Decreases low side drops No defrost, less heat at condenser Low Pressure Limit Mode 6 Ramps up and trips Small decrease No air leaving external- ly, yellow battery High Pressure Limits 3. What two observations were the most important? Why? The most important observations were high side pressure behavior and which protective limit was reached in each mode. Together, these showed how the system responded as load increased. 4. What do those observations tell you about how the system is behaving? The observations show that as system load increased, the system could not effectively reject heat. High load modes caused rapid high side pressure rise and protective shutdown, while lower load modes showed falling low side pres- sure and reduced performance. This indicates a heat rejection limitation rather than a control instability. 5. Which operating mode exposed the issue most clearly, and what changed in that mode compared to the others? Mode 6 exposed the issue because it places the largest heat load on the system. When the system cannot reject that heat, high side pressure rises quickly and the system reaches a protection limit. Part 3 – Diagnosis and Recommended Service 6. Based on what you observed, what type of problem does this look like? A. Control or command problem B. Refrigerant flow or metering problem C. Heat transfer problem Why? What makes the other options less likely? The problem gets worse as heat load increases and appears across multiple modes. This rules out a single expan- sion valve or control issue and points to limited heat rejection at a heat exchanger. consulab.com info@consulab.com 80 91-EV-2000 SA-18 - LEVEL III — Abnormal Heat Transfer 7. When the system is under higher load, where does the excess heat need to go? ☐ Through the compressor ☐ Through an expansion or metering device Through a heat exchanger ☐ Through a sensor or control input 8. Based on your observations, what do you believe the most likely diagnosis is? What service or inspection would you recommend next? The most likely diagnosis is reduced heat transfer at a heat exchanger. The next step is to inspect the affected heat exchanger for restricted airflow or poor heat transfer and verify temperature change across it to confirm that heat is not being effectively rejected. consulab.com info@consulab.com 81 91-EV-2000 Section 3 – Battery Flow Assessment Section 3 – Battery Flow Assessment 1. Why are EV batteries typically cooled using a glycol loop instead of direct HVAC refrigerant cooling? A. Refrigerant systems cannot cool batteries B. Glycol provides slower, more stable temperature control C. Batteries require airflow for cooling D. Glycol eliminates the need for a pump 2. Refrigerant-based battery cooling is most appropriate when: A. Battery heat load is high or conditions are extreme B. Cabin comfort is the only priority C. The battery is already cold D. Battery heat load is low 3. A thermal system shows rapidly rising high side pressure only when heat demand is high. Technician A says this points to a heat rejection or heat transfer limitation. Technician B says this most likely indicates a sensor display error. Which technician is correct? A. Technician A only B. Technician B only C. Both Technician A and Technician B D. Neither Technician A nor Technician B 4. What component circulates glycol through the battery cooling loop? A. Blower motor B. Compressor C. Glycol pump D. Expansion valve 5. If glycol leaves the battery warmer than it entered, that indicates glycol is: A. Releasing heat to the battery B. Absorbing heat from the battery C. Not transferring heat D. Bypassing the battery consulab.com info@consulab.com 82 91-EV-2000 Section 3 – Battery Flow Assessment 6. In a glycol radiator cooling strategy, the radiator’s main job is to: A. Increase battery temperature quickly B. Compress refrigerant vapor C. Create superheat D. Release heat to outside air 7. Reduced heat transfer at a heat exchanger has been identified. Technician A says the next step is to immediately replace the compressor. Technician B says airflow and temperature change across the heat exchanger should be verified first. Which technician is correct? A. Technician A only B. Technician B only C. Both Technician A and Technician B D. Neither Technician A nor Technician B 8. The main purpose of a chiller in EV thermal management is to: A. Store refrigerant B. Replace the evaporator C. Transfer heat between glycol and refrigerant without mixing fluids D. Increase battery electrical output 9. Which measurement pair best confirms that the chiller is cooling the glycol? A. Cabin vent temperature vs ambient temperature B. Compressor inlet temp vs compressor outlet temp C. Battery surface temp vs outside air temp D. Glycol inlet to chiller vs glycol outlet from chiller 10. A PTC heater is useful because it: A. Requires refrigerant to operate B. Self-regulates and reduces output as temperature rises C. Always produces constant heat at high temperatures D. Works only during extreme ambient temperatures 11. Using the same glycol loop for both heating and cooling is helpful because it: A. Eliminates the radiator B. Guarantees constant battery temperature C. Prevents heat transfer D. Reduces system complexity and hardware consulab.com info@consulab.com 83 91-EV-2000 Section 3 – Battery Flow Assessment 12. If glycol temperature increases after the PTC heater but the battery does not warm, the first thing to verify is: A. Refrigerant charge B. Glycol flow reaching the battery C. Cabin blower speed D. Expansion valve position 13. A strong “known-good” check for glycol circulation is observing: A. Superheat at the external heat exchanger when under a higher load B. Compressor RPM C. A clear temperature change across a loop that removes heat from a warm component D. Cabin air temperature when the blower is on high 14. In a combined operation where battery heat is used to help warm the cabin, which statement is most accurate? A. Heat is collected from the battery and delivered to cabin air through a heat exchanger path B. Heat is created only by the compressor C. Cabin heating must always use a PTC heater D. The glycol loop is not used 15. A system shows different behavior under different operating conditions rather than the same symptoms every time. Technician A says this makes low refrigerant charge less likely. Technician B says low refrigerant charge usually caus- es similar symptoms across conditions. Which technician is correct? A. Technician A only B. Technician B only C. Both Technician A and Technician B D. Neither Technician A nor Technician B consulab.com info@consulab.com 84 91-EV-2000 SA-19 - LEVEL II — Battery Cooling Strategies and System Prioritization SA-19 - LEVEL II — Battery Cooling Strategies and System Prioritization Instructor Notes Teaching Suggestions • Provide the Mode 6 diagram for comparison, or have students reuse the schematic they created in SA-14. • Emphasize heat movement and destination within a system, not memorizing mode names. • When reviewing Part 3, prompt students with: - “Where is the battery heat going in each case?” - “What changes when the battery load increases?” • Allow students to discuss answers verbally before committing to written responses for Questions 16–18. Practical Applications • Mirrors how real EVs start with the simplest cooling strategy and add capacity only when needed. • Helps students understand why battery cooling is managed differently than cabin comfort. • Prepares students to recognize why a system changes operating strategy during high load, hot weather, or combined cabin/battery demands. consulab.com info@consulab.com 85 91-EV-2000 SA-19 - LEVEL II — Battery Cooling Strategies and System Prioritization Answers Objective: Compare how refrigerant- and glycol-based battery cooling strategies are prioritized under high load or high temperature conditions. Material Required: EV-2000, power supply, Blank Schematic with ID diagram, Mode 6 diagram Part 1 – Trace the Flow to Cool the Batteries Use the Blank Schematic with ID diagram to complete the following: 1. Draw arrows showing the refrigerant path starting from the compressor Label and color where the refrigerant is: - RED: high pressure vapor - YELLOW: high pressure liquid - DARK BLUE: low pressure liquid - LIGHT BLUE: low pressure vapor 2. Label where the refrigerant “absorbs heat” 3. Label where the refrigerant “releases heat” 4. Label where subcooling occurs 5. Label where superheat occurs 6. Draw arrows showing the glycol path starting from the glycol pump Label and color where glycol is: - GREEN: cold - PURPLE: warm 7. Put an X on any components not used during this mode. Check your work with your instructor before moving on. consulab.com info@consulab.com 86 91-EV-2000 SA-19 - LEVEL II — Battery Cooling Strategies and System Prioritization Part 2 – Heat Transfer Check Match each component or location with its correct function or description in Mode 9: Battery Cool: HVAC + Glycol Radiator. Each answer is used once. B 1. Compressor A. Location where refrigerant releases heat and changes state E 2. Chiller B. Raises refrigerant pressure and temperature to enable heat rejection A 3. External Heat Exchanger C. Removes heat from glycol using outside air before returning to the battery D 4. Glycol Pump D. Circulates glycol through the battery, chiller, and radiator G 5. Suction Line (Compressor Inlet) E. Location where refrigerant absorbs heat during battery cooling C 6. Glycol Radiator F. Meters refrigerant and creates the pressure drop needed for evaporation F 7. Expansion Valve (EEV) G. Location where refrigerant should be low pressure vapor with superheat Part 3 – Compare Battery Cooling Strategies Using the Mode 9 schematic from Part 1 and the Mode 6 diagram, sort the statements below by placing each one into the column(s) where it best belongs. • Designed for low to moderate battery heat load • Designed for high battery heat load or extreme conditions • Outside air is the final destination for battery heat • Used when battery temperature rises too quickly • Rejects heat using refrigerant only • Uses multiple heat sinks • Lower energy consumption • Highest battery cooling capacity Battery Cooling: HVAC Battery Cooling: HVAC + Gylcol Radiator • Designed for low to moderate battery heat load • Outside air is the final destination for battery heat • Rejects heat using refrigerant only • Lower energy consumption • Designed for high battery heat load or extreme conditions • Outside air is the final destination for battery heat • Used when battery temperature rises too quickly • Uses multiple heat sinks • Highest battery cooling capacity 8. Why does the system use Mode 6 whenever possible instead of going straight to Mode 9? The system starts with the simpler cooling strategy because it can remove battery heat using fewer components and less energy. If this is enough to keep the battery temperature under control, there is no reason to run the com- pressor or add more complexity. consulab.com info@consulab.com 87 91-EV-2000 SA-19 - LEVEL II — Battery Cooling Strategies and System Prioritization 9. What operating condition would most likely cause the system to switch from Mode 6: HVAC to Mode 9: HVAC + Glycol Radiator? When the battery is producing more heat than the glycol system alone can remove, the system increases cooling capacity by using the refrigerant loop. 10. In addition to Mode 6: HVAC and Mode 9: HVAC +Gylcol Radiator, is there another system configuration the vehicle could use to remove battery heat? Describe where the battery heat would go in this case. Yes. If the cabin needs heat at the same time, in Mode 8 the system can direct battery heat into the cabin. In this case, the heat from the battery is used to warm the cabin air instead of being rejected to the outside consulab.com info@consulab.com 88 91-EV-2000 SA-20 - LEVEL II — Battery and Cabin Cooling SA-20 - LEVEL II — Battery and Cabin Cooling Instructor Notes Teaching Suggestions • This assignment is not about identifying the “correct” cooling priority by memory, but about using evidence from the schematic to determine which system appears more protected under high demand. • When reviewing Question 5, prompt students with: - Which system has more than one way to reject heat? - What does that suggest about system protection when demand increases? • Reinforce that the terms “primary” and “secondary” describe system behavior, not importance to the driver. • In Part 2, guide students away from thinking in terms of failure. The system is reallocating cooling capacity, not shut- ting down. • For the driving scenario in Question 10, remind students they are analyzing thermal response, not electrical control strategy or fault logic. Practical Applications • During hard acceleration in hot conditions, real EVs often reduce cabin cooling output while maintaining normal vehicle performance. • Technicians may receive customer concerns such as “A/C gets weak during hard driving” even though no faults are present. • Understanding how cooling capacity is distributed across parallel heat rejection paths helps prevent misdiagnosis of normal system behavior as a failure. • Operating cooling systems at high capacity draws additional energy, which can temporarily reduce vehicle range, especially during aggressive driving or extreme ambient temperatures. Drivers may notice reduced range estimates during hot weather not because of a fault, but because energy is being used to manage battery temperature. Under- standing this tradeoff helps technicians explain why customer concerns about reduced range or weaker A/C can be normal system behavior, not a malfunction. consulab.com info@consulab.com 89 91-EV-2000 SA-20 - LEVEL II — Battery and Cabin Cooling Answers Objective: Trace combined refrigerant and coolant flow paths and explain how the system prioritizes cooling demands. Material Required: EV-2000, power supply, Mode 10 diagram Part 1 – Identify Prioritized Cooling Use the Mode 10 diagram to complete the following: 1. Draw arrows showing active refrigerant and glycol flow paths 2. Label where heat is absorbed vs released 3. Circle the main component(s) responsible for battery cooling radiator, chiller 4. Star the main component(s) responsible for cabin cooling evaporator, external heat exchanger 5. Based on the active components and flow paths shown, rank which system, battery or cabin cooling, appears to be most protected when demand is high. Justify your ranking using evidence from the diagram. - Highest priority = battery cooling, because it has both the chiller and the radiator to release heat. - Secondary priority = cabin evaporator, because it only has the heat exchanger to release heat. Part 2 – Evidence of System Protection 6. Which system has more than one active heat removal path? ☐ Cabin cooling Battery cooling 7. Which system continues to receive cooling even when another system is also demanding cooling? ☐ Cabin cooling Battery cooling 8. Which system would be affected first if overall cooling capacity had to be reduced? Cabin cooling ☐ Battery cooling 9. One heat removal path becomes restricted. What does the system do with the remaining available cooling capacity? The system shifts cooling to the best way to manage the battery, so its heat can still be removed. 10. It is a hot summer day. The vehicle has been cruising at city speeds, then the driver floors the accelerator to merge onto the freeway, causing a sudden increase in power demand. Based on this scenario, describe how the thermal system responds A. Which system(s) experience a sudden increase in heat load? Battery cooling B. Which cooling paths become critical during this event? The glycol loop, radiator, and heat exchanger C. What change might the driver notice if the system reaches its cooling limit? If the system reaches its cooling limit, the driver might notice reduced cabin cooling performance, such as warmer air from the vents, while the vehicle continues to operate normally. consulab.com info@consulab.com 90 91-EV-2000 SA-21 - LEVEL III — Diagnosing Glycol Performance SA-21 - LEVEL III — Diagnosing Glycol Performance Instructor Notes Teaching Suggestions • Before students begin, insert Fault 2 Gylcol Pump Does Not Turn On on the EV-2000. This fault can appear in multi- ple operating modes, so students should not assume the issue is isolated to a single mode. • Encourage students to select modes involving both the cabin and the battery to match the customer concern, rather than defaulting to a battery only or cabin only mode. • Emphasize that this is a time based diagnosis. In Part 2, students must allow the EV-2000 to remain in each selected mode long enough for the concern to develop, since the customer reports the issue occurring “after driving for a while.” • Reinforce that students are being evaluated on how they observe, compare, and reason, not on how quickly they name a fault (especially if they see right away that the pump isn’t running). Practical Applications • Real EV customer concerns often involve delayed symptoms, where heating or cooling seems normal at first and then degrades during longer drives or higher demand. • In mixed cabin and battery operation, technicians must understand how system prioritization can cause a battery related issue to impact cabin comfort without an immediate shutdown. • This assignment mirrors real diagnostic practice, where technicians must reproduce the concern under the correct operating conditions and duration, rather than relying on a single snapshot reading. consulab.com info@consulab.com 91 91-EV-2000 SA-21 - LEVEL III — Diagnosing Glycol Performance Answers Objective: Diagnose a thermal system concern by analyzing time based behavior and comparing cabin and battery per- formance across multiple operating modes Material Required: EV-2000, power supply, clamp on thermometer Part 1 – Customer Intake Review the customer concern below and gather the appropriate materials to diagnose. Customer Concern: “After driving for a while, the car doesn’t seem to cool or heat like it should. Sometimes the cabin temperature changes slowly, and then the battery temperature warning light came on during a long drive.” 1. Based on the customer concern, which system(s) must be evaluated? Select all that apply. Cabin heating and cooling Battery temperature management ☐ Refrigerant pressures only ☐ Electrical control logic only 2. Which operating modes would be most useful to investigate first? Mode Mode Justification: Mode 6, 8, 9, or 10 are all acceptable answers. And effects of this fault can be seen in Modes 4-10. These modes involve both the cabin and the battery, which matches the customer concern. 3. Why would checking only a single mode be insufficient for this concern? Checking more than one mode helps determine whether the issue affects the system the same way under different conditions. consulab.com info@consulab.com 92 91-EV-2000 SA-21 - LEVEL III — Diagnosing Glycol Performance Part 2 – System Observation Using the operating modes selected in Part 1, run the system long enough for the customer concern to appear. Record observations for each below. NOTE: Since multiple modes can be correct for this assignment, only Mode 8 and Mode 10 have been chosen for this answer key. First, describe what happens over time, not just at startup, in both Modes. Mode: 8 – Cabin Heat and Batt Cool: HVAC Cabin Temperature Behavior: Cabin warms at first, then heat becomes weak Battery Temperature Behavior: Battery temperature slowly increases; Battery Light from Yellow to Red to Flashing Red Do temperatures across the battery cooling system ap- pear to change meaningfully, or remain similar at multiple points? ☐ Temperatures change noticeably Temperatures remain similar Other Observations: • EV3 to Chiller to Accumulator iced • Glycol Pump not spinning Mode: 10 – Cabin Cool + Batt Cool: HVAC + Glycol Radiator Cabin Temperature Behavior: Air from vents is not as cold after extended operation Battery Temperature Behavior: Battery temperature slowly increases; Battery Light from Yellow to Red to Flashing Red Do temperatures across the battery cooling system ap- pear to change meaningfully, or remain similar at multiple points? ☐ Temperatures change noticeably Temperatures remain similar Other Observations: • Glycol Pump not spinning Compare what you observed between the two modes. 4. Does the concern appear faster, slower, or about the same between modes? The concern appears faster in Mode 10 and takes longer to show up in Mode 8. 5. Does changing modes reduce, worsen, or mask the concern? Changing modes alters how the problem appears, with Mode 8 partially masking it and Mode 10 making it more noticeable. consulab.com info@consulab.com 93 91-EV-2000 SA-21 - LEVEL III — Diagnosing Glycol Performance 6. Based on all observations above, check all statements that apply: Heat appears to be generated, but its effect is delayed ☐ Performance degrades gradually rather than immediately ☐ The concern appears differently depending on the mode ☐ The issue affects both cabin performance and battery temperature ☐ Other observation: Part 3 – Diagnosis and Recommended Service 7. Based on all observations collected across both modes, what type of system problem best explains the customer concern? ☐ Refrigerant flow or metering issue ☐ Airflow or heat exchange limitation Heat transport issue within the battery thermal system ☐ Electrical control or sensor issue Explanation: The battery temperature increased over time while temperatures across the cooling system did not change much, which shows heat is not being moved away effectively. 8. Based on your observations, how does the system respond when it cannot remove heat from the battery as intended? ☐ The system shuts down immediately The system continues operating with reduced performance ☐ The system increases cabin output to compensate The system changes how heating and cooling capacity is shared Explanation: The system keeps running but cabin performance becomes weaker or inconsistent as the battery tem- perature rises. 9. The original concern included both cabin performance and battery temperature. Why would a problem in the bat- tery cooling system still affect cabin heating or cooling performance? Because the system prioritizes protecting the battery, so when the battery cannot be cooled properly, heating or cooling capacity is reduced or redirected away from the cabin. 10. What repair or corrective action would most directly address the root cause of this concern? Restore proper glycol circulation by repairing or replacing the glycol pump and then verify that battery temperature and system performance return to normal. consulab.com info@consulab.com 94 91-EV-2000 SA-22 - LEVEL III — Diagnosing Battery Cooling Performance SA-22 - LEVEL III — Diagnosing Battery Cooling Performance Instructor Notes Teaching Suggestions • Ensure Fault 7 Expansion Valve EV3 Opens Less Than Requested is active before students begin. • Emphasize this is a time-based diagnosis; students must allow each mode to run long enough for symptoms to de- velop. • Encourage students to test multiple modes, including at least one combined cabin + battery mode, to match the customer concern. • Reinforce the consistent pattern across all relevant modes: - Low side pressure trends low (often hitting limits) - High side pressure remains lower than expected (does not climb) - Battery cooling is weak, not absent - Severity increases with demand (especially Modes 9 and 8) • Use this pattern to guide elimination: - Airflow restriction is unlikely (high side would rise) - Compressor underperformance is unlikely (would affect all modes more uniformly) - Control logic errors are unlikely (behavior is gradual and thermodynamic, not binary) • Remind students that clamp on thermometers are used for confirmation, not exploration; placement should be intentional and justified. Practical Applications • Technicians must distinguish between reduced capacity and no operation to avoid unnecessary component replace- ment. • Cross mode comparison is critical in modern EV thermal systems where cabin and battery cooling are tightly inte- grated. • This assignment reflects real world diagnostics where faults do not immediately set codes or cause shutdowns, but instead show time and load dependent symptoms. consulab.com info@consulab.com 95 91-EV-2000 SA-22 - LEVEL III — Diagnosing Battery Cooling Performance Answers Objective: Diagnose a battery cooling performance concern by analyzing time-based system behavior and comparing battery and cabin operation across multiple operating modes. Material Required: EV-2000, power supply, clamp on thermometer Part 1 – Customer Intake Review the customer concern below and gather the appropriate materials to diagnose. Customer Concern: “The battery cooling performance is weak during extended driving, especially when the air condi- tioning is turned on.” 1. Which vehicle systems are directly involved? Select all. Cabin air conditioning system Battery thermal management system ☐ Power electronics cooling ☐ Heating system ☐ Defrost system 2. Identify which types of components could influence battery cooling when cabin A/C is active. Select All. Compressor Chiller Glycol pump(s) Heat exchangers Expansion valve(s) ☐ Airflow devices (fans, airflow paths) 3. List two observations you would expect to see if the system is able to cool the battery, but not well enough under combined demand. Battery temperature decreases at first but does not drop enough to meet demand, especially during longer oper- ation. Cooling performance gets worse over time when cabin A/C is operating, even though the system remains on and responsive. consulab.com info@consulab.com 96 91-EV-2000 SA-22 - LEVEL III — Diagnosing Battery Cooling Performance Part 2 - System Testing Test at least two of the following modes. Compare battery cooling effectiveness and system stability between these modes. At least one must involve combined cabin and battery cooling. NOTE: Fault 7 will show symptoms in all. ☐ Mode 6 – Battery Cooling with HVAC ☐ Mode 8 – Cabin Heating + Battery Cooling Mode 9 – Advanced Battery Cooling Mode 10 – Cabin Cooling + Battery Cooling Record your observations in the following table, use the notes section to document temperature changes, effects over time, or unusual behavior. Consider the question: Does the concern appear to be mode specific or demand related? Mode: 9: Batt Cool: HVAC + Gylcol Radiator Mode: 10: Cabin Cool + Batt Cool: HVAC + Glycol Rad Battery Cooling Effectiveness ☐ Normal Reduced ☐ No cooling Battery Cooling Effectiveness ☐ Normal Reduced ☐ No cooling System Behavior Overtime ☐ Stable ☐ Gradually degrades Reaches a system limit System Behavior Overtime ☐ Stable Gradually degrades ☐ Reaches a system limit Low-side Pressure Behavior ☐ Normal Lower than expected ☐ Increasing Low-side Pressure Behavior ☐ Normal Lower than expected ☐ Increasing High-Side Pressure Behavior ☐ Higher than expected Normal to lower than expected ☐ Increasing High-Side Pressure Behavior ☐ Higher than expected Normal to lower than expected ☐ Increasing Notes: low-side pressure is dropping Notes: low-side pressure is dropping abnormally Part 3 – Focused Battery Cooling Test To determine whether the concern is caused by shared system demand or limited batterycooling capacity, perform a focused test using Mode 9: Advanced Battery Cooling. operate the system long enough for system behavior to develop. Observe battery cooling effectiveness, pressure behavior, and system stability over time. Measurement Value Low-side Pressure Low and trending downward until tripped at 6 PSI Low-side Pressure converted Temperature 0° F / 18° C High-side Pressure Normal to slightly low, 125 and decreasing High-side Pressure Converted Temperature 100° F / 38° C Notes: (include time-based changes, system limits, or any calculations) Even when battery cooling is prioritized, cooling remains weak. Low side pressure drops rapidly confirming the issue is not caused by cabin demand. Elevated superheat. consulab.com info@consulab.com 97 91-EV-2000 SA-22 - LEVEL III — Diagnosing Battery Cooling Performance 4. When cabin demand is removed and battery cooling is prioritized (Mode 9), battery cooling: ☐ Improves significantly Remains reduced ☐ Stops completely Explain your answer: In Mode 9, battery cooling does not improve even when cabin demand is removed. Low-side pressure keeps drop- ping, showing the issue is within the battery cooling system, not caused by cabin A/C demand. 5. Based on the system behavior observed so far, where should you place your clamp on thermometers to confirm the source of the restriction? On the refrigerant line entering the battery chiller On the refrigerant line leaving the battery chiller On the glycol inlet and outlet of the battery chiller 6. Based on: - Customer concern - Mode testing (Modes 6, 10, and 9) - Pressure behavior - Component level temperature measurements What is your final diagnosis? Use evidence to support that choice. The battery cooling concern is caused by a restricted expansion valve supplying refrigerant to the battery chiller. Ev- idence shows cooling is present but reduced across Modes 6, 10, and 9, with consistently low low side pressure and no corresponding rise in high side pressure, indicating refrigerant starvation rather than a control or airflow issue. Componentlevel temperature measurements confirm a weak temperature change across the chiller, consistent with limited refrigerant flow. consulab.com info@consulab.com 98 91-EV-2000 SA-23 - LEVEL III — Restricted vs. Blocked Chiller Feed SA-23 - LEVEL III — Restricted vs. Blocked Chiller Feed Instructor Notes Teaching Suggestions • Insert Fault 8 Expansion Valve EV3 Stuck Shut before students begin. • Remind students this assignment builds directly on SA-22 and uses the same measurement points for comparison. • Data from SA-22 on a restricted EV3 could be provided to save time rather than having them look back. • Emphasize that the fault is known; the task is to differentiate blocked vs restricted using evidence. • Reinforce expected blocked valve behavior vs. other types of faults: - Battery cooling is minimal or absent - Chiller glycol ΔT is near zero - Refrigerant temperatures across the chiller are nearly identical - Stress that pressures alone are not sufficient; the key differentiator is lack of heat transfer at the chiller. • If students focus only on lowside pressure, redirect attention to refrigerant movement and chiller temperature change. Practical Applications • In real EVs, a chiller supply line can become blocked by dirt or debris, dried-out material breaking apart inside the A/C drier, or a valve that fails internally. • Example: On some Tesla and Hyundai/Kia EV platforms, a blocked chiller or refrigerant valve can cause battery temperature to rise during DC fast charging or extended highway driving, even though the A/C system appears to operate. • Technicians must distinguish between reduced cooling capacity (restricted flow) and no heat transfer (blocked flow) to avoid unnecessary compressor or control module replacement. • This assignment mirrors real diagnostics where battery cooling faults may not set immediate codes, requiring tem- perature and pressure comparison instead of scantool reliance. consulab.com info@consulab.com 99 91-EV-2000 SA-23 - LEVEL III — Restricted vs. Blocked Chiller Feed Answers Objective: Differentiate between restricted and blocked refrigerant flow to the battery chiller by comparing battery cooling performance, pressure trends, and chiller temperature changes. Material Required: EV-2000, power supply, clamp on thermometer, Mode 9 diagram, SA-22 data Part 1 – Collect Data 1. You collected data on a restricted EV3 in SA-22. Before measuring anything, write a prediction by filling in the blanks: When EV3 is blocked, battery cooling will stop because refrigerant flow to the chiller is blocked. Collect data in Mode 9 : Batt Cool: HVAC + Glycol Radiator. Run the system long enough for symptoms of the problems to fully develop, then compare the results to the data collected in SA-22 when the valve was restricted. Observation Restricted EV3 (SA-22) Blocked EV3 Battery Cooling Effectiveness ☐ Normal Reduced ☐ No cooling ☐ Normal Reduced ☐ No cooling System Behavior Over Time ☐ Stable Gradually degrades ☐ Reaches a system limit ☐ Stable ☐ Gradually degrades Reaches a system limit Low-side Pressure 10 PSI 10 PSI until tripped Pressure Converted Temperature 7° F / -14° C 7° F / -14° C High-side Pressure 125 PSI 125 PSI Pressure Converted Temperature 100° F / 38° C 100° F / 38° C Refrigerant line entering battery chiller 41° F / 5° C 46° F / 8° C Refrigerant line leaving battery chiller 50° F / 10° C 53° F / 12° C Glycol inlet to battery chiller 68° F / 20° C 75° F / 24° C Glycol outlet from battery chiller 59° F / 15° C 70° F / 21° C 2. Calculate and record: - Chiller glycol ΔT = (glycol inlet − glycol outlet) = • Restricted = 68° F - 59° F = 9° F • Blocked = 75° F – 70° F = 5° F - Refrigerant line ΔT across chiller = (refrig in − refrig out) = • Restricted = 41° F – 50° F = 9 ° F • Blocked = 46° F - 53° F = 6° F consulab.com info@consulab.com 100 91-EV-2000 SA-23 - LEVEL III — Restricted vs. Blocked Chiller Feed Part 2 – Blocked vs. Restricted 3. Circle the best match: - Battery cooling when EV3 is blocked compared to restricted is: greater / less / similar - Chiller glycol ΔT when EV3 is blocked compared to restricted is: greater / less / similar - Refrigerant line ΔT across the chiller when EV3 is blocked compared to restricted is: greater / less / similar. - Low side refrigerant pressure when EV3 is blocked compared to restricted is: greater / less / similar 4. Which single observation best proves “blocked” rather than “restricted” expansion valve? ☐ Battery cooling is reduced Low side pressure drops immediately ☐ Chiller glycol ΔT drops immediately ☐ High side pressure drops immediately ☐ Refrigerant ΔT drops immediately 5. Explain why the observations above indicate a blocked expansion valve rather than a restricted one. In the explana- tion, reference refrigerant movement through the chiller and heat transfer to the battery cooling loop. This observation indicates a blocked expansion valve rather than a restricted one because refrigerant flow through the chiller is completely interrupted. When EV3 is blocked, the low side pressure drops immediately and reaches a safe limit condition, triggering a warning and creating a vacuum. With no refrigerant movement through the chiller, temperatures on both sides remain nearly the same and the glycol temperature change is minimal, indicating little to no heat transfer to the battery cooling loop. In the restricted condition, some refrigerant flow was still present, allowing reduced but measurable heat transfer across the chiller. consulab.com info@consulab.com 101 91-EV-2000 SA-24 - LEVEL III — Diagnosing Heat Rejection Limitations SA-24 - LEVEL III — Diagnosing Heat Rejection Limitations Instructor Notes Teaching Suggestions • Insert Fault 1 Restricted Airflow: External Heat Exchanger before students begin. • Reinforce that the key indicator in this scenario is time-based pressure behavior, not an immediate failure or single abnormal reading. • When operating in Mode 2 and/or Mode 3 with Fault 1 active, after a certain amount of time, usually after 6 to 10 minutes, superheat may become very low and can sometimes even become negative. This can happen because the EEVs have a minimum opening value they can reach in order to prevent the compressor from entering a vacuum condition. In a real vehicle application, a scroll compressor would normally vary its rotational speed instead. • Guide students to recognize that steadily rising high side pressure across multiple modes points to a heat rejection issue, not a refrigerant metering or control problem. • If students focus too early on expansion valves or pumps, redirect attention to cross mode patterns and where heat must be released from the system before further measurements are taken. • Accept reasonable variation in measurement locations and data values; evaluation should be based on justification and reasoning, not exact numbers. Practical Applications • Restricted airflow at the front heat exchanger is a common real-world issue caused by road debris, leaves, insects, or packed dirt. • In real EVs, this condition often appears as normal cooling at startup followed by degraded performance during highway driving, hot weather, or DC fast charging. • Technicians must distinguish heat rejection problems from refrigerant flow or control issues to avoid unnecessary replacement of compressors, valves, or electronic modules. consulab.com info@consulab.com 102 91-EV-2000 SA-24 - LEVEL III — Diagnosing Heat Rejection Limitations Answers Objective: Diagnose a cooling performance concern by analyzing time-based system behavior, comparing operation across multiple modes, and using targeted measurements to determine where energy transfer is limited. Material Required: EV-2000, power supply, clamp on thermometer, … Part 1 – Customer Intake Review the customer concern below and gather the appropriate materials to diagnose the issue. Customer Concern: “Cooling performance is normal at first, but quickly degrades under sustained use. After several minutes of operation, the system appears to struggle, and cooling effectiveness drops even though the system continues running.” 1. Based on the symptoms observed, which type of system limitation is most likely? ☐ Refrigerant flow into the system Heat rejection from the system ☐ Coolant circulation within the system ☐ Control logic preventing operation 2. What observations do you expect to see as a result of this concern? Select all. High side pressure rises steadily instead of stabilizing ☐ Low side pressure drops rapidly to very low values ☐ Symptoms are isolated to battery only cooling modes Cooling performance degrades over time rather than failing immediately Similar symptoms appear across multiple operating modes System reaches a pressure or temperature limit under sustained operation ☐ Cooling improves when demand increases ☐ Little to no temperature change in the glycol loop 3. Which operating modes should be tested first to best reproduce this concern? Select two and explain why. Answers will vary. Strong answers typically select Mode 1 and Mode 10 or Mode 1 and Mode 9 because these modes require the system to reject large amounts of heat. When heat cannot be released fast enough, high side pressure rises over time and cooling performance drops, making the problem easy to observe across both cabin and battery operation. consulab.com info@consulab.com 103 91-EV-2000 SA-24 - LEVEL III — Diagnosing Heat Rejection Limitations Part 2 – Mode Selection & Pattern Identification Operate the EV-2000 in the selected modes and allow each mode to run long enough for system behavior to develop. Record cooling or heating effectiveness and observe how system pressures change over time. Observation Mode: 1: Cabin Cool: Heat Pump Mode: 9: Batt Cool: HVAC + Glycol Rad System Performance ☐ Normal Reduced ☐ No cooling/heating ☐ Normal Reduced ☐ No cooling/heating Behavior Over Time ☐ Stable ☐ Gradually degrades Reaches a limit ☐ Stable Gradually degrades ☐ Reaches a limit High-side Pressure Trend ☐ Stable Slowly rising ☐ Rapidly rising ☐ Stable ☐ Slowly rising Rapidly rising Low-side Pressure Trend ☐ Stable Slight rise ☐ Slight drop ☐ Stable Slight rise ☐ Slight drop Notes Noticeable immediately, hits system limit after 4 or so minutes High-side pressure is a concern, low-side rises too. 4. Does system performance degrade immediately or over time? Immediate ☐ Gradual 5. Are similar symptoms observed across multiple modes? Yes ☐ No 6. Which side of the system shows the most abnormal behavior? High side ☐ Low side ☐ Both 7. Based on the system behavior and pressure patterns observed so far, which area of the system should be evaluated next to confirm the source of the limitation, and why? The front heat rejection area should be evaluated next because high side pressure continues to rise instead of sta- bilizing across multiple modes. Measuring temperature change across the front heat exchanger will show whether heat is being released effectively to the air. consulab.com info@consulab.com 104 91-EV-2000 SA-24 - LEVEL III — Diagnosing Heat Rejection Limitations Part 3 – Targeted Measurements and Diagnosis Based on the system behavior and pressure patterns observed in Part 2, select and perform targeted temperature measurements to evaluate where energy transfer may be limited. Choose measurement locations that directly relate to the abnormal system behavior identified earlier. Record the measurements below. Columns may be used for different modes or collecting measurements over time. NOTE: Data and choices will vary. Measurement Location Mode 1: Cabin Cool: Heat Pump Mode 9: Batt Cool: HVAC + Glycol Rad Exchanger Inlet 120° F / 49° C 94° F / 34° C Exchanger Outlet 126° F / 52° C 96° F / 36° C Chiller Inlet n/a 56° F / 13° C Chiller Outlet n/a 56° F / 13° C Radiator Inlet n/a 75° F / 24° C Radiator Outlet n/a 75° F / 24° C Evaporator Inlet 41° F / 5° C n/a Evaporator Outlet 57° F / 14° C n/a 8. Based on the pressure trends and temperature measurements collected, what type of system limitation is present? Which observation or measurement most strongly supports this conclusion, and why? The system has trouble getting rid of heat. The strongest sign is that the high side pressure keeps going up while the temperature change across the heat exchangers stays small. This shows the system is running but heat is not leaving the system like it should. 9. What corrective action would be recommended to restore normal system operation? The recommended action is to check and fix anything blocking airflow or heat transfer at the front heat exchanger (condenser). After the issue is fixed, the system should be tested again to make sure pressures and temperatures return to normal. consulab.com info@consulab.com 105 91-EV-2000 SA-25 - LEVEL III — Diagnosing Cabin Evaporator Flow Limitations SA-25 - LEVEL III — Diagnosing Cabin Evaporator Flow Limitations Instructor Notes Teaching Suggestions • Insert Fault 5 Expansion Valve EV2 Opens Less Than Requested before students begin. • Emphasize that this fault is subtle and does not produce dramatic pressure spikes or system shutdowns. • Reinforce that students should focus on where cooling is weak, not just whether the system is running. • Guide students to recognize the diagnostic pattern: - Low side pressure significantly below normal - High side pressure relatively normal - Very high calculated superheat - Reduced cabin cooling without system limits • Remind students that superheat is the primary diagnostic tool in this assignment, not pressure alone. • If students suspect undercharge, prompt them to use subcooling as a crosscheck. • Accept small variations in calculated values; grading should prioritize reasoning and justification, not exact numbers. Practical Applications • Restricted expansion valves feeding cabin evaporators are a common real-world fault caused by contamination, debris, or internal wear. • In actual vehicles, this condition often presents as “the A/C runs but doesn’t cool well”, with no warning lights or codes. • Technicians who rely only on pressure readings may misdiagnose this as low refrigerant or airflow issues. • This assignment trains students to use superheat and subcooling together to confirm refrigerant metering problems and avoid unnecessary component replacement. • The diagnostic approach used here mirrors professional HVAC and EV service practices. consulab.com info@consulab.com 106 91-EV-2000 SA-25 - LEVEL III — Diagnosing Cabin Evaporator Flow Limitations Answers Objective: Diagnose a cabin cooling performance concern by analyzing mode specific behavior, pressure trends, and superheat/subcooling data to distinguish a localized refrigerant flow limitation from systemwide faults. Material Required: EV-2000, power supply, clamp on thermometer, calculator, … Part 1 – Customer Intake Review the customer concern below and gather the appropriate materials to diagnose the issue. Customer Concern: “Cabin cooling is weak even though the system appears to be operating normally. Cooling perfor- mance is noticeably reduced, but there are no obvious pressure spikes or system shutdowns.” 1. Based on the symptoms observed, which type of system limitation is most likely? Refrigerant flow into the system ☐ Heat rejection from the system ☐ Coolant circulation within the system ☐ Control logic preventing operation 2. What observations do you expect to see as a result of this concern? Select all. Low side pressure decreases compared to normal operation Cabin cooling performance is reduced while the system continues to operate ☐ Highside pressure rises steadily instead of stabilizing Cooling performance is reduced without the system reaching pressure limits ☐ Symptoms are isolated to battery only cooling modes Limited or inconsistent temperature change across the cabin evaporator ☐ Cooling improves when demand increases ☐ Little to no temperature change in the glycol loop 3. Which operating modes should be tested first to best reproduce this concern? Select two and explain why. Answers will vary. Mode 1 and Mode 10 should be tested first. Mode 1 directly uses the cabin evaporator, so it makes weak cabin cooling easier to see. Mode 10 also shows poor cabin cooling while the rest of the system still works, which helps confirm that the problem is mainly affecting the cabin side. consulab.com info@consulab.com 107 91-EV-2000 SA-25 - LEVEL III — Diagnosing Cabin Evaporator Flow Limitations Part 2 – Mode Selection & Pattern Identification Operate the EV-2000 in the selected modes and allow each mode to run long enough for system behavior to develop. Record cooling or heating effectiveness and observe how system pressures change over time. Observation Mode: 1: Cabin Cool: Heat Pump Mode: 10: Cabin Cool + Batt Cool System Performance ☐ Normal Reduced ☐ No cooling/heating ☐ Normal Reduced ☐ No cooling/heating Behavior Over Time ☐ Stable Gradually degrades ☐ Reaches a limit ☐ Stable Gradually degrades ☐ Reaches a limit High-side Pressure Trend ☐ Stable ☐ Increasing Decreasing Stable ☐ Increasing ☐ Decreasing Low-side Pressure Trend ☐ Stable ☐ Increasing Decreasing ☐ Stable ☐ Increasing Decreasing Notes Gradual decrease in pressure, low cooling Minimal impact on pressure, poor cabin cooling 4. Does system performance degrade immediately or over time? ☐ Immediate Gradual 5. Are similar symptoms observed across multiple modes? Yes ☐ No 6. Which side of the system shows the most abnormal behavior? ☐ High side Low side ☐ Both 7. Based on the system behavior and pressure patterns observed so far, which area of the system should be evaluated next to confirm the source of the limitation, and why? The cabin cooling area should be checked next because cabin cooling is weak while the rest of the system still runs normally. The low side pressure drops without a big change in high side pressure, which suggests the problem is affecting the cabin side instead of the whole system. consulab.com info@consulab.com 108 91-EV-2000 SA-25 - LEVEL III — Diagnosing Cabin Evaporator Flow Limitations Part 3 – Targeted Measurements and Diagnosis Based on the system behavior and pressure patterns observed in Part 2, select and perform targeted temperature measurements to evaluate where energy transfer may be limited. Choose measurement locations that directly relate to the abnormal system behavior identified earlier. Record the measurements below. Columns may be used for different modes or collecting measurements over time. NOTE: Data and choices will vary. Measurement Location Mode 1: Cabin Cool: Heat Pump Mode 10: Cabin Cool + Batt Cool Low-side Pressure 6 PSI 20 PSI Low-side Saturation Temp -0° F / −18° C 22° F / -5.4° C Evaporator Outlet Temp 72° F / 22° C 54° F / 12° C Calculated Superheat 72° F – 0° F = 72° F 54° F –22° F = 32° F High-side Pressure 150 PSI 150 PSI High-side Saturation Temp 111 °F / 44 °C 111° F / 44° C Liquid Line Temp 72° F / 22° C 102° F / 39° C Calculated Subcooling 111° F -72° F = 39° F 111° F - 102° F = 9° F 8. Based on the pressure trends and temperature measurements collected, what type of system limitation is present? Which observation or measurement most strongly supports this conclusion, and why? The system has a refrigerant flow limitation going into the cabin evaporator. The strongest evidence is the very low low side pressure of 6 PSI and the high superheat. This shows that not enough refrigerant is entering the evaporator, so it cannot absorb enough heat even though the system is running. 9. What corrective action would be recommended to restore normal system operation? The recommended action is to inspect and repair or replace the expansion valve that controls refrigerant flow to the cabin evaporator. After the repair, the system should be tested again to make sure pressures, superheat, and cabin cooling return to normal. consulab.com info@consulab.com 109 91-EV-2000 SA-26 - LEVEL III — Diagnosing a Severe Cabin Cooling Failure SA-26 - LEVEL III — Diagnosing a Severe Cabin Cooling Failure Instructor Notes Teaching Suggestions • Insert Fault 6 Expansion Valve EV2 Stuck Shut before students begin. • Emphasize that this scenario represents a worst-case cabin cooling complaint, not a gradual performance issue. • Guide students to focus on how quickly the system reacts with immediate limits and vacuum behavior as key indica- tors. • Encourage comparison with prior assignments: - SA-25: weak cooling, system still stable - SA-26: no cooling, rapid limits, extreme pressure behavior • Reinforce that 0 PSI suction combined with very high superheat is not normal operation and must be explained by lack of refrigerant movement, not airflow or control logic. • If students suggest low charge, prompt them to use subcooling as a crosscheck. • Accept variation in exact values; grading should be based on pattern recognition and justification, not precision. Practical Applications • Modern EVs such as the Ford Mach E and Hyundai Ioniq 5 use multiple electronically controlled expansion valves to manage separate cabin and battery cooling paths. • In real vehicles, a failure like this often presents as: - No cabin cooling - Rapid compressor shutdown or protection - Battery cooling still operating normally • This can mislead technicians into suspecting a compressor or control fault. • This assignment trains students to recognize that: - Extreme low side pressure + very high superheat indicates no refrigerant flow, not insufficient airflow or heat rejection. - Correct diagnosis prevents unnecessary replacement of compressors, sensors, or control modules. consulab.com info@consulab.com 110 91-EV-2000 SA-26 - LEVEL III — Diagnosing a Severe Cabin Cooling Failure Answers Objective: Analyze system behavior, pressure trends, and temperature data to determine the cause of a complete cabin cooling failure and differentiate a localized refrigerant flow issue from other thermal system limitations. Material Required: EV-2000, power supply, clamp on thermometer, calculator … Part 1 – Customer Intake Review the customer concern below and gather the appropriate materials to diagnose the issue. Customer Concern: “Cabin cooling does not work at all, and the system quickly shuts down or reaches a limit shortly after being turned on. In combined cabin and battery cooling operation, the battery continues to cool normally, but the cabin does not cool.” 1. Based on the symptoms observed, which type of system limitation is most likely? Refrigerant flow into the system ☐ Heat rejection from the system ☐ Coolant circulation within the system ☐ Control logic preventing operation 2. What observations do you expect to see as a result of this concern? Select all. Low side pressure drops rapidly and may pull into a vacuum Cabin cooling does not occur at all ☐ High side pressure rises steadily instead of stabilizing ☐ Cooling performance is reduced without the system reaching pressure limits System reaches a pressure or safety limit very quickly Battery cooling continues to operate while cabin cooling does not ☐ Cooling improves when demand increases Little to no temperature change across the cabin evaporator 3. Which operating modes should be tested first to best reproduce this concern? Select two and explain why. Mode 1 and Mode 10 should be tested first. Mode 1 should show the problem quickly because it depends on the cabin cooling system. Mode 10 should help show whether the issue affects only the cabin or if battery cooling still works at the same time. consulab.com info@consulab.com 111 91-EV-2000 SA-26 - LEVEL III — Diagnosing a Severe Cabin Cooling Failure Part 2 – Mode Selection & Pattern Identification Operate the EV-2000 in the selected modes and allow each mode to run long enough for system behavior to develop. Record cooling or heating effectiveness and observe how system pressures change over time. Observation Mode: 1: Cabin Cool: Heat Pump Mode: 10: Cabin Cool + Batt Cool Cabin Cooling ☐ Normal Reduced None ☐ Normal ☐ Reduced None Battery Cooling n/a Normal Reduced ☐ None System Behavior ☐ Stable ☐ Gradually Degrading Reaches System Limit ☐ Stable Gradually Degrading ☐ Reaches System Limit Low-side Pressure Trend ☐ Stable ☐ Increasing Decreasing ☐ Stable ☐ Increasing Decreasing High-Side Pressure Trend ☐ Stable ☐ Increasing Decreasing ☐ Stable ☐ Increasing Decreasing Notes Hit trigger limit rapidly; accumulator boils Battery cooling appears functional 4. Does system performance degrade immediately or over time? Immediate ☐ Gradual 5. Are similar symptoms observed across multiple modes? ☐ Yes No 6. Which side of the system shows the most abnormal behavior? ☐ High side Low side ☐ Both 7. Based on the system behavior and pressure patterns observed so far, which area of the system should be evaluated next to confirm the source of the limitation, and why? The cabin cooling side of the system should be checked next. In Mode 1, the system reaches a limit very quickly and the low side pressure drops, which shows the cabin evaporator is not absorbing heat. In Mode 10, battery cooling still works while cabin cooling does not, which suggests the problem is isolated to the cabin side and not the entire system. consulab.com info@consulab.com 112 91-EV-2000 SA-26 - LEVEL III — Diagnosing a Severe Cabin Cooling Failure Part 3 – Targeted Measurements and Diagnosis Based on the system behavior and pressure patterns observed in Part 2, select and perform targeted temperature measurements to evaluate where energy transfer may be limited. Choose measurement locations that directly relate to the abnormal system behavior identified earlier. Record the measurements below. Columns may be used for different modes or collecting measurements over time. NOTE: Data choices will vary. Measurement Location Mode 1: Cabin Cool: Heat Pump Mode 10: Cabin Cool + Batt Cool Low-side Pressure 0 PSI 15 PSI Low-side Saturation Temp -18° F / -28° C 16° F / -9° C Evaporator Outlet Temp 66° F / 19° C 55° F / 13° C Calculated Superheat 66° F – (-18° F) = 84° F 55° F - 16° F = 39° F High-side Pressure 150 PSI 150 PSI High-side Saturation Temp 111 °F / 44 °C 111 °F / 44 °C External Heat Exchanger Outlet Temp 64° F / 18° C 100 ° F / 38° C Calculated Subcooling 111° F – 64° F = 47° F 111 ° F - 100° F = 11° F 8. Based on the pressure trends and temperature measurements collected, what type of system limitation is present? Which observation or measurement most strongly supports this conclusion, and why? The system has a complete refrigerant flow blockage to the cabin evaporator. The strongest evidence is the low side pressure dropping to 0 PSI and the very high superheat of 84°F. This shows that refrigerant is not entering the evaporator at all, so it cannot absorb heat even though the system is running. 9. What corrective action would be recommended to restore normal system operation? The recommended action is to inspect and repair or replace the expansion valve that feeds the cabin evaporator. Since no refrigerant is reaching the evaporator, fixing the valve should restore normal refrigerant flow. After the repair, the system should be tested again to confirm normal pressures, superheat, and cabin cooling. consulab.com info@consulab.com 113 91-EV-2000 SA-27 - LEVEL III — Diagnosing a Cabin Heating Limitation SA-27 - LEVEL III — Diagnosing a Cabin Heating Limitation Instructor Notes Teaching Suggestions • Insert Fault 11 Restricted Airflow: Cabin Condenser before students begin the assignment. • Emphasize that this scenario represents a system that starts working normally, then quickly overheats and limits • Encourage students to focus on where heat is supposed to go during heating, not just on whether the compressor is running. • If students suggest refrigerant flow or expansion valve faults, guide them back to: - Rising high side pressure - Have them feel the rising line temperatures - Similar behavior across multiple heating modes • Remind students that: - This fault looks very different from SA-25 and SA-26 - Neither superheat nor subcooling is the primary diagnostic tool for this fault type • Accept a range of student wording; correct answers should explain what is happening and why, not use exact termi- nology. Practical Applications • In real vehicles, restricted airflow at a condenser can be caused by: - Debris or dust buildup - Blocked ducting or filters - Damaged or restricted air paths • EVs that use internal condensers for cabin heating (such as Tesla Model 3 / Model Y, Ford Mach E, and Hyundai Ioniq 5) can show: - Cabin heat that fades after a short time - Rapid pressure rise and compressor limiting - Reduced performance during combined cabin and battery operation • This assignment trains students to recognize that: - A hot condenser and rising pressure means heat is not leaving the system - The fix is often airflow related, not a refrigerant or electrical repair - Correct diagnosis helps prevent unnecessary replacement of compressors or expansion valves. consulab.com info@consulab.com 114 91-EV-2000 SA-27 - LEVEL III — Diagnosing a Cabin Heating Limitation Answers Objective: Analyze heating performance, pressure trends, and temperature measurements to determine why cabin heat- ing degrades or reaches limits during operation, and to distinguish airflow related heat removal problems from refriger- ant flow or control issues. Material Required: EV-2000, power supply, clamp on thermometer, calculator … Part 1 – Customer Intake Review the customer concern below and gather the appropriate materials to diagnose the issue. Customer Concern: “Cabin heating performance is weak or stops after running for a short time. The system appears to be working at first, but pressure and temperature rise quickly and the system reaches a limit. In some operating modes, heat output is reduced even though the system continues to run.” 1. Based on the symptoms observed, which type of system limitation is most likely? ☐ Refrigerant flow into the system Heat rejection from the system ☐ Coolant circulation within the system ☐ Control logic preventing operation 2. What observations do you expect to see as a result of this concern? Select all. ☐ Low side pressure drops rapidly and may pull into a vacuum ☐ Cabin cooling does not occur at all High side pressure rises quickly instead of stabilizing System reaches a temperature or pressure limit after a short time ☐ Cooling performance is reduced without the system reaching limits ☐ Battery cooling continues to operate while cabin cooling does not ☐ Cooling improves when demand increases Cabin condenser temperature becomes very high 3. Which operating modes should be tested first to best reproduce this concern? Select two and explain why. Mode 2 and Mode 3 should be tested first because both rely on the cabin condenser to reject heat during heating. These modes should make pressure and temperature rise quickly if heat cannot leave the cabin side. Mode 8 can also help show reduced heating when the system is under mixed demand. consulab.com info@consulab.com 115 91-EV-2000 SA-27 - LEVEL III — Diagnosing a Cabin Heating Limitation Part 2 – Mode Selection & Pattern Identification Operate the EV-2000 in the selected modes and allow each mode to run long enough for system behavior to develop. Record heating effectiveness and observe how system pressures change over time. Observation Mode: 2: Cabin Heat: Heat Pump Mode: 3: Cabin Heat + Defrost Cabin Heating ☐ Normal ☐ Reduced None ☐ Normal ☐ Reduced None System Behavior Over Time ☐ Stable ☐ Gradually Degrading Reaches System Limit ☐ Stable ☐ Gradually Degrading Reaches System Limit Low-side Pressure Trend ☐ Stable ☐ Increasing Decreasing ☐ Stable ☐ Increasing Decreasing High-Side Pressure Trend ☐ Stable Increasing ☐ Decreasing ☐ Stable Increasing ☐ Decreasing Notes Hit trigger limit rapidly; high-side increasing rapidly; lines hot to touch Hit trigger limit rapidly; high-side increasing rapidly; lines hot to touch 4. Does system performance degrade immediately or over time? ☐ Immediate Gradual 5. Are similar symptoms observed across multiple heating modes? Yes ☐ No 6. Which side of the system shows the most abnormal behavior? High side ☐ Low side ☐ Both 7. Based on the system behavior and pressure patterns observed so far, which area of the system should be evaluated next to confirm the source of the limitation, and why? The cabin heat rejection area should be checked next because high side pressure and temperature increase quickly in multiple heating modes. The cabin condenser becomes very hot and the system reaches limits, which suggests heat is not being released properly from the cabin side. consulab.com info@consulab.com 116 91-EV-2000 SA-27 - LEVEL III — Diagnosing a Cabin Heating Limitation Part 3 – Targeted Measurements and Diagnosis Based on the system behavior and pressure patterns observed in Part 2, select and perform targeted temperature mea- surements to evaluate where energy transfer may be limited. Record the measurements below. Columns may be used for different modes or collecting measurements over time. NOTE: Data choices will vary. Measurement Location Mode 2: Cabin Heat: Heat Pump Mode 3: Cabin Heat + Defrost High-side Pressure 250 PSI 200 PSI, increasing High-side Saturation Temp 145° F / 63° C 131° F / 55° C Cabin Condenser Inlet 176° F / 80° C 170° F / 77° C Cabin Condenser Outlet 122° F / 50° C 120° F / 49° C External Heat Exchanger Outlet 115° F / 46° C 66° F / 19° C Calculated Subcooling 145° F - 122° F = 23° F 131° F - 120° F = 11° F 8. How might this fault affect battery cooling performance in a setting like Mode 8: Cabin Heat and Batt Cool: HVAC? In Mode 8, battery cooling could also be reduced because the system cannot release heat properly. Since the cabin condenser is too hot and the high side pressure is high, the refrigerant cannot cool down enough to work well in other parts of the system. This can limit how much heat the chiller can remove from the battery loop. 9. Based on the pressure trends and temperature measurements collected, what is the problem? What would be rec- ommended to restore normal operating conditions? The system has trouble getting rid of heat at the cabin condenser. The high side pressure goes up and the condens- er gets very hot, which causes the system to reach a limit. To fix the problem, airflow across the cabin condenser should be restored by removing any blockage or fixing the airflow path. After that, the system should be tested again to make sure pressures return to normal. 10. How do these symptoms of restricted airflow at the cabin condenser differ from restricted airflow at the cabin evaporator? In your answer, compare at least two of the following: system pressures, component temperatures, and overall heating or cooling performance. When airflow is restricted at the cabin condenser, high side pressure increases and the condenser becomes very hot because heat cannot leave the system. When airflow is restricted at the cabin evaporator, the problem is on the low side, and the evaporator cannot absorb heat properly, which causes weak cooling or heating. Overall, condens- er airflow problems mainly affect heat rejection and pressure, while evaporator airflow problems mainly affect heat absorption and cabin performance. consulab.com info@consulab.com 117 91-EV-2000 Advanced Battery Flow Section Assessmen Advanced Battery Flow Section Assessment 1. Why do EV thermal systems typically begin battery cooling with the simplest available strategy? A. To reduce cabin comfort complaints B. To minimize energy use while meeting thermal needs C. To avoid using refrigerant systems D. To prevent battery heating during charging 2. Which statement best explains why a system can be running but still fail to cool effectively? A. The compressor is undersized B. Heat has no place to go C. Cabin airflow is too high D. Refrigerant pressure is too low 3. Which observation most strongly indicates that battery cooling is being prioritized over cabin comfort? A. Cabin air becomes colder B. Battery temperature remains controlled while cabin output weakens C. Compressor shuts off D. Low side pressure drops to zero 4. Which system feature allows higher battery cooling capacity under heavy demand? A. A single evaporator B. One heat rejection path C. Multiple heat sinks D. Lower operating pressure 5. Two technicians discuss why cabin cooling weakens during aggressive driving on a hot day. Technician A says this al- ways indicates a system fault. Technician B says this can be normal system behavior due to battery cooling priority. Who is correct? A. Technician A only B. Technician B only C. Both Technician A and Technician B D. Neither Technician A nor Technician B consulab.com info@consulab.com 118 91-EV-2000 Advanced Battery Flow Section Assessmen 6. Why is time-based observation critical in EV thermal diagnostics? A. Sensors need time to initialize B. Control logic must reset C. Pressures are delayed electronically D. Many issues appear only after sustained operation 7. What does it suggest if battery temperature continues rising even after cabin demand is reduced? A. Cabin airflow restriction B. Normal operation C. Battery cooling capacity is insufficient D. Refrigerant overcharge 8. Which observation most strongly distinguishes a heat transfer problem from a refrigerant flow restriction? A. Gradually rising high side pressure B. Immediate loss of cooling C. Compressor not running D. Electrical warning lights 9. Which situation is most likely normal system behavior, not a fault? A. Cabin cooling weakens during heavy battery load B. System shuts down immediately C. Battery cooling stops completely D. Compressor never starts 10. Two technicians discuss why multiple operating modes must be tested during diagnosis. Technician A says testing different modes shows how the system responds to different demands. Technician B says testing multiple modes helps reveal whether behavior is demand related or fault related. Who is correct? A. Technician A only B. Technician B only C. Both Technician A and Technician B D. Neither Technician A nor Technician B consulab.com info@consulab.com 119 91-EV-2000 Diagrams and Schematics Diagrams and Schematics consulab.com info@consulab.com 120 91-EV-2000 Diagrams and Schematics EV -2 0 00 - M O D E 1 = C A B IN C O O L : H EA T P U M P © C on su La b Ed uc at ec h In c, 2 02 6. A ll ri gh ts r es er ve d C O M PR ES SO R C A BI N C O N D EN SE R EV A P BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E EX PA N SI O N V A LV E EV 2 EX PA N SI O N V A LV E EV 1 EX PA N SI O N V A LV E EV 3 BA TT ER Y C H IL LE R H EA TE R C O RE RA D IA TO R PU M P A C C U M U LA TO R PT C H EA TE R EX TE RN A L H EA T EX C H A N G ER A IR FL O W SH U TT ER H IG H P RE SS U RE V A PO RI ZE D R EF RI G ER A N T H IG H P RE SS U RE L IQ U ID R EF RI G ER A N T LO W P RE SS U RE L IQ U ID R EF RI G ER A N T LO W P RE SS U RE V A PO RI ZE D R EF RI G ER A N T C O LD G LY C O L W A RM H O T G LY C O L LE G EN D M od e 1 = C ab in C oo l : H ea t Pu m p consulab.com info@consulab.com 121 91-EV-2000 Diagrams and Schematics EV -2 0 00 - M O D E 2 = C A B IN H EA T : H EA T P U M P © C on su La b Ed uc at ec h In c, 2 02 6. A ll ri gh ts r es er ve d C O M PR ES SO R C A BI N C O N D EN SE R EV A P BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E EX PA N SI O N V A LV E EV 2 EX PA N SI O N V A LV E EV 1 EX PA N SI O N V A LV E EV 3 BA TT ER Y C H IL LE R H EA TE R C O RE RA D IA TO R PU M P A C C U M U LA TO R PT C H EA TE R EX TE RN A L H EA T EX C H A N G ER A IR FL O W SH U TT ER H IG H P RE SS U RE V A PO RI ZE D R EF RI G ER A N T H IG H P RE SS U RE L IQ U ID R EF RI G ER A N T LO W P RE SS U RE L IQ U ID R EF RI G ER A N T LO W P RE SS U RE V A PO RI ZE D R EF RI G ER A N T C O LD G LY C O L W A RM H O T G LY C O L LE G EN D M od e 2 = C ab in H ea t : H ea t Pu m p consulab.com info@consulab.com 122 91-EV-2000 Diagrams and Schematics EV -2 0 00 - M O D E 3 = C A B IN H EA T + D EF R O S T : H EA T P U M P © C on su La b Ed uc at ec h In c, 2 02 6. A ll ri gh ts r es er ve d C O M PR ES SO R C A BI N C O N D EN SE R EV A P BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E EX PA N SI O N V A LV E EV 2 EX PA N SI O N V A LV E EV 1 EX PA N SI O N V A LV E EV 3 BA TT ER Y C H IL LE R H EA TE R C O RE RA D IA TO R PU M P A C C U M U LA TO R PT C H EA TE R EX TE RN A L H EA T EX C H A N G ER A IR FL O W SH U TT ER H IG H P RE SS U RE V A PO RI ZE D R EF RI G ER A N T H IG H P RE SS U RE L IQ U ID R EF RI G ER A N T LO W P RE SS U RE L IQ U ID R EF RI G ER A N T LO W P RE SS U RE V A PO RI ZE D R EF RI G ER A N T C O LD G LY C O L W A RM H O T G LY C O L LE G EN D M od e 3 = C ab in H ea t + D ef ro st : H ea t Pu m p consulab.com info@consulab.com 123 91-EV-2000 Diagrams and Schematics EV -2 0 00 - M O D E 4 = C A B IN H EA T : P T C + G LY C O L R A D IA T O R © C on su La b Ed uc at ec h In c, 2 02 6. A ll ri gh ts r es er ve d C O M PR ES SO R C A BI N C O N D EN SE R EV A P BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E EX PA N SI O N V A LV E EV 2 EX PA N SI O N V A LV E EV 1 EX PA N SI O N V A LV E EV 3 BA TT ER Y C H IL LE R H EA TE R C O RE RA D IA TO R PU M P A C C U M U LA TO R PT C H EA TE R EX TE RN A L H EA T EX C H A N G ER A IR FL O W SH U TT ER H IG H P RE SS U RE V A PO RI ZE D R EF RI G ER A N T H IG H P RE SS U RE L IQ U ID R EF RI G ER A N T LO W P RE SS U RE L IQ U ID R EF RI G ER A N T LO W P RE SS U RE V A PO RI ZE D R EF RI G ER A N T C O LD G LY C O L W A RM H O T G LY C O L LE G EN D M od e 4 = C ab in H ea t : P TC + G ly co l R ad ia to r consulab.com info@consulab.com 124 91-EV-2000 Diagrams and Schematics EV -2 0 00 - M O D E 5 = B A T T C O O L : G LY C O L R A D IA T O R © C on su La b Ed uc at ec h In c, 2 02 6. A ll ri gh ts r es er ve d C O M PR ES SO R C A BI N C O N D EN SE R EV A P BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E EX PA N SI O N V A LV E EV 2 EX PA N SI O N V A LV E EV 1 EX PA N SI O N V A LV E EV 3 BA TT ER Y C H IL LE R H EA TE R C O RE RA D IA TO R PU M P A C C U M U LA TO R PT C H EA TE R EX TE RN A L H EA T EX C H A N G ER A IR FL O W SH U TT ER H IG H P RE SS U RE V A PO RI ZE D R EF RI G ER A N T H IG H P RE SS U RE L IQ U ID R EF RI G ER A N T LO W P RE SS U RE L IQ U ID R EF RI G ER A N T LO W P RE SS U RE V A PO RI ZE D R EF RI G ER A N T C O LD G LY C O L W A RM H O T G LY C O L LE G EN D M od e 5 = Ba tt er y C oo l : G ly co l R ad ia to r consulab.com info@consulab.com 125 91-EV-2000 Diagrams and Schematics EV -2 0 00 - M O D E 6 : B A T T C O O L : H V A C © C on su La b Ed uc at ec h In c, 2 02 6. A ll ri gh ts r es er ve d C O M PR ES SO R C A BI N C O N D EN SE R EV A P BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E EX PA N SI O N V A LV E EV 2 EX PA N SI O N V A LV E EV 1 EX PA N SI O N V A LV E EV 3 BA TT ER Y C H IL LE R H EA TE R C O RE RA D IA TO R PU M P A C C U M U LA TO R PT C H EA TE R EX TE RN A L H EA T EX C H A N G ER A IR FL O W SH U TT ER H IG H P RE SS U RE V A PO RI ZE D R EF RI G ER A N T H IG H P RE SS U RE L IQ U ID R EF RI G ER A N T LO W P RE SS U RE L IQ U ID R EF RI G ER A N T LO W P RE SS U RE V A PO RI ZE D R EF RI G ER A N T C O LD G LY C O L W A RM H O T G LY C O L LE G EN D M od e 6 = Ba tt er y C oo l : H VA C consulab.com info@consulab.com 126 91-EV-2000 Diagrams and Schematics EV -2 0 00 - M O D E 7 = B A T T H EA T : P T C + G LY C O L © C on su La b Ed uc at ec h In c, 2 02 6. A ll ri gh ts r es er ve d C O M PR ES SO R C A BI N C O N D EN SE R EV A P BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E EX PA N SI O N V A LV E EV 2 EX PA N SI O N V A LV E EV 1 EX PA N SI O N V A LV E EV 3 BA TT ER Y C H IL LE R H EA TE R C O RE RA D IA TO R PU M P A C C U M U LA TO R PT C H EA TE R EX TE RN A L H EA T EX C H A N G ER A IR FL O W SH U TT ER H IG H P RE SS U RE V A PO RI ZE D R EF RI G ER A N T H IG H P RE SS U RE L IQ U ID R EF RI G ER A N T LO W P RE SS U RE L IQ U ID R EF RI G ER A N T LO W P RE SS U RE V A PO RI ZE D R EF RI G ER A N T C O LD G LY C O L W A RM H O T G LY C O L LE G EN D M od e 7 = Ba tt er y H ea t : P TC + G ly co l consulab.com info@consulab.com 127 91-EV-2000 Diagrams and Schematics EV -2 0 00 - M O D E 8 = C A B IN H EA T A N D B A T T C O O L : H V A C © C on su La b Ed uc at ec h In c, 2 02 6. A ll ri gh ts r es er ve d C O M PR ES SO R C A BI N C O N D EN SE R EV A P BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E EX PA N SI O N V A LV E EV 2 EX PA N SI O N V A LV E EV 1 EX PA N SI O N V A LV E EV 3 BA TT ER Y C H IL LE R H EA TE R C O RE RA D IA TO R PU M P A C C U M U LA TO R PT C H EA TE R EX TE RN A L H EA T EX C H A N G ER A IR FL O W SH U TT ER H IG H P RE SS U RE V A PO RI ZE D R EF RI G ER A N T H IG H P RE SS U RE L IQ U ID R EF RI G ER A N T LO W P RE SS U RE L IQ U ID R EF RI G ER A N T LO W P RE SS U RE V A PO RI ZE D R EF RI G ER A N T C O LD G LY C O L W A RM H O T G LY C O L LE G EN D M od e 8 = C ab in H ea t & B at te ry C oo l : H VA C consulab.com info@consulab.com 128 91-EV-2000 Diagrams and Schematics EV -2 0 00 - M O D E 9 = B A T T C O O L : H V A C + G LY C O L R A D IA T O R © C on su La b Ed uc at ec h In c, 2 02 6. A ll ri gh ts r es er ve d C O M PR ES SO R C A BI N C O N D EN SE R EV A P BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E EX PA N SI O N V A LV E EV 2 EX PA N SI O N V A LV E EV 1 EX PA N SI O N V A LV E EV 3 BA TT ER Y C H IL LE R H EA TE R C O RE RA D IA TO R PU M P A C C U M U LA TO R PT C H EA TE R EX TE RN A L H EA T EX C H A N G ER A IR FL O W SH U TT ER H IG H P RE SS U RE V A PO RI ZE D R EF RI G ER A N T H IG H P RE SS U RE L IQ U ID R EF RI G ER A N T LO W P RE SS U RE L IQ U ID R EF RI G ER A N T LO W P RE SS U RE V A PO RI ZE D R EF RI G ER A N T C O LD G LY C O L W A RM H O T G LY C O L LE G EN D M od e 9 = Ba tt er y C oo l : H VA C + G ly co l R ad ia to r consulab.com info@consulab.com 129 91-EV-2000 Diagrams and Schematics EV -2 0 00 - M O D E 10 = C A B IN C O O L + B A T T C O O L : H V A C + G LY C O L R A D IA T O R © C on su La b Ed uc at ec h In c, 2 02 6. A ll ri gh ts r es er ve d C O M PR ES SO R C A BI N C O N D EN SE R EV A P BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E EX PA N SI O N V A LV E EV 2 EX PA N SI O N V A LV E EV 1 EX PA N SI O N V A LV E EV 3 BA TT ER Y C H IL LE R H EA TE R C O RE RA D IA TO R PU M P A C C U M U LA TO R PT C H EA TE R EX TE RN A L H EA T EX C H A N G ER A IR FL O W SH U TT ER H IG H P RE SS U RE V A PO RI ZE D R EF RI G ER A N T H IG H P RE SS U RE L IQ U ID R EF RI G ER A N T LO W P RE SS U RE L IQ U ID R EF RI G ER A N T LO W P RE SS U RE V A PO RI ZE D R EF RI G ER A N T C O LD G LY C O L W A RM H O T G LY C O L LE G EN D M od e 10 = C ab in C oo l + B at te ry C oo l : H VA C + G ly co l R ad ia to r consulab.com info@consulab.com 130 91-EV-2000 Diagrams and Schematics EV -2 0 00 - B LA N K S C H EM A T IC W IT H ID © C on su La b Ed uc at ec h In c, 2 02 6. A ll ri gh ts r es er ve d C O M PR ES SO R C A BI N C O N D EN SE R EV A P BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E EX PA N SI O N V A LV E EV 2 EX PA N SI O N V A LV E EV 1 EX PA N SI O N V A LV E EV 3 BA TT ER Y C H IL LE R H EA TE R C O RE RA D IA TO R PU M P A C C U M U LA TO R PT C H EA TE R EX TE RN A L H EA T EX C H A N G ER A IR FL O W SH U TT ER H IG H P RE SS U RE V A PO RI ZE D R EF RI G ER A N T H IG H P RE SS U RE L IQ U ID R EF RI G ER A N T LO W P RE SS U RE L IQ U ID R EF RI G ER A N T LO W P RE SS U RE V A PO RI ZE D R EF RI G ER A N T C O LD G LY C O L W A RM H O T G LY C O L LE G EN D Bl an k D ia gr am W ith ID consulab.com info@consulab.com 131 91-EV-2000 Diagrams and Schematics EV -2 0 00 - FA U LT S C H EM A T IC © C on su La b Ed uc at ec h In c, 2 02 6. A ll ri gh ts r es er ve d C O M PR ES SO R C A BI N C O N D EN SE R EV A P BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E BY PA SS V A LV E EX PA N SI O N V A LV E EV 2 EX PA N SI O N V A LV E EV 1 EX PA N SI O N V A LV E EV 3 BA TT ER Y C H IL LE R H EA TE R C O RE RA D IA TO R PU M P A C C U M U LA TO R PT C H EA TE R EX TE RN A L H EA T EX C H A N G ER A IR FL O W SH U TT ER H IG H P RE SS U RE V A PO RI ZE D R EF RI G ER A N T H IG H P RE SS U RE L IQ U ID R EF RI G ER A N T LO W P RE SS U RE L IQ U ID R EF RI G ER A N T LO W P RE SS U RE V A PO RI ZE D R EF RI G ER A N T C O LD G LY C O L W A RM H O T G LY C O L LE G EN D F3 : 10 % F4 : F7 : 7% -1 0% F8 : F1 : 25 % F1 0 : F5 : 5% -2 0% F6 : F1 1 : 5 0% F9 : F1 2 : 5 0% F2 : F1 3 : Fa ul t Sc he m at ic consulab.com info@consulab.com 132 91-EV-2000 Glossary Glossary Battery cool: HVAC: A mode that uses the refrigerant loop via the chiller to cool glycol feeding the battery. Battery cool: HVAC + glycol radiator: A mode that adds a radiator for extra heat rejection during battery cooling. Battery heat: PTC + glycol: A mode that uses the PTC heater to warm glycol for battery heating. Bypass valve: A valve that reroutes fluid around a component instead of through it, allowing the system to control tem- perature, reduce flow resistance, or change operating modes without stopping fluid flow. Cabin heat + battery cool: HVAC: A mixed-demand mode balancing cabin heating and battery cooling. Change of state: The process where refrigerant changes between liquid and vapor phases to enable heating or cooling. Chiller (thermal exchange unit): A heat exchanger that transfers energy between the refrigerant and glycol loops. Compressor: An electrically driven compressor that pressurizes refrigerant for the heat pump cycle. Condenser: A heat exchanger where the refrigerant releases heat and condenses back into a liquid, rejecting heat to the environment. Condensation: The process in which a vapor changes back into a liquid as it gives up latent heat, releasing or expelling heat in a way that produces a warming effect. Digital contact thermometer: A clamp-on tool for measuring pipe temperatures. Electronic Expansion Valve (EEV): A device that electronically meters refrigerant flow for optimal system performance. Enthalpy: The heat content per unit mass, used to explain energy transfer in refrigeration cycles. Evaporator: A heat exchanger where the refrigerant absorbs heat and evaporates, cooling the surrounding air or fluid. Evaporation: The process in which the refrigerant absorbs latent heat inside the evaporator as it changes from a liquid to a vapor, producing a cooling effect as it boils into a gas. consulab.com info@consulab.com 133 91-EV-2000 Glossary Glycol: A type of antifreeze liquid used in the cooling loop of electric vehicles to transfer heat away from components like batteries and power electronics; it typically consists of ethylene glycol mixed with water and additives to prevent freezing and corrosion. Heat exchanger: A device that transfers heat between two fluids (such as refrigerant and glycol) without mixing them, enabling thermal management. Heat pump: A reversible refrigeration system that transfers heat for heating or cooling purposes. Heater core: A component that delivers heat to the cabin using the glycol loop. Latent heat: The hidden energy that changes the state of the refrigerant without changing the temperature. Parallel: A configuration where fluid has more than one path to flow through at the same time, allowing flow to split be- tween components operating side-by-side. PSIG (Pounds per Square Inch Gauge): A pressure measurement that indicates pressure relative to atmospheric pres- sure, meaning it shows how much above or below atmospheric pressure a system is. Used instead of absolute pressure when servicing automotive systems. PTC heater (Positive Temperature Coefficient): An electric heater that uses a material whose resistance increases with temperature, allowing it to self-regulate heat output; in EV systems, it is used to provide supplemental heating when needed. Radiator: A component that rejects heat from the glycol loop to the environment. Refrigerant: A chemical fluid used in heating and cooling systems that circulates through the system to absorb heat during evaporation and release heat during condensation, enabling temperature control. Saturation: The temperature where a refrigerant reaches its boiling or condensing point. This is where liquid and vapor can coexist, because a change of state is occurring as latent heat is absorbed or released. Sensible heat: Heat that produces a measurable change in temperature that can be read on a thermometer without causing a change in the substance’s state. Series: A configuration where fluid flows through components one after another in a single path, so the same flow passes through each component in sequence. Service ports: Access points for refrigerant service and recovery operations. Shut-off valves (refrigerant): Valves that isolate sections of the refrigerant circuit for service. consulab.com info@consulab.com 134 91-EV-2000 Glossary Subcooling: “Sensible heat” removed from a liquid below saturation. Superheat: “Sensible heat” added to a vapor above saturation. Thermal Expansion Valve (TXV): A metering device in refrigeration and heat pump systems that regulates the flow of liquid refrigerant into the evaporator based on temperature and pressure, ensuring efficient heat absorption and pre- venting evaporator flooding. Transistor: An electronic switching or control device used to regulate current flow; in the EV-2000, it is used to control power to the PTC heater. 400-6330 Zéphirin-Paquet St. Québec QC G2C 0M3 Canada © ConsuLab Educatech Inc, 2026. All rights reserved. Tips for Operating the Trainer Student Assignments Instructor Notes and Answers General Instructor Note Environmental Impact of Answer Key SA-1 - LEVEL I — Components of an EV Thermal Management System Instructor Notes Answers SA-2 - LEVEL I — How a Scroll Compressor Works Instructor Notes Answers SA-3 - LEVEL I — Superheating and Subcooling Instructor Notes Answers SA-4 - LEVEL I — Cooling the Cabin Instructor Notes Answers SA-5 - LEVEL I — Heating the Cabin Instructor Notes Answers SA-6 - LEVEL II — Electronic Expansion Valves Instructor Notes Answers SA-7 - LEVEL II — Cabin Heat and Defrost Instructor Notes Answers SA-8 - LEVEL I — Heating the Cabin Without Refrigerant Instructor Notes Answers Section 1 - Cabin Components Assessment SA-9 - LEVEL II — Effects of a Restricted Expansion Valve Instructor Notes Answers SA-10 - LEVEL III — Restricted vs. Blocked Expansion Valves Instructor Notes Answers SA-11 - LEVEL III — Diagnosing the Evaporator Instructor Notes Answers SA-12 - LEVEL III — Diagnosing a Cabin Performance Concern Instructor Notes Answers Section 2 – Cabin Flow Assessment SA-13 - LEVEL I — Introduction to Battery Cooling Instructor Notes Answers SA-14 - LEVEL II — Battery Cooling with HVAC Instructor Notes Answers SA-15 - LEVEL I — Introduction to Battery Heating Instructor Notes Answers SA-16 - LEVEL II — Glycol Heating System Performance Analysis Instructor Notes Answers SA-17 - LEVEL II — Heat Transfer from the Battery to the Cabin Instructor Notes Answers SA-18 - LEVEL III — Abnormal Heat Transfer Instructor Notes Answers Section 3 – Battery Flow Assessment SA-19 - LEVEL II — Battery Cooling Strategies and System Prioritization Instructor Notes Answers SA-20 - LEVEL II — Battery and Cabin Cooling Instructor Notes Answers SA-21 - LEVEL III — Diagnosing Glycol Performance Instructor Notes Answers SA-22 - LEVEL III — Diagnosing Battery Cooling Performance Instructor Notes Answers SA-23 - LEVEL III — Restricted vs. Blocked Chiller Feed Instructor Notes Answers SA-24 - LEVEL III — Diagnosing Heat Rejection Limitations Instructor Notes Answers SA-25 - LEVEL III — Diagnosing Cabin Evaporator Flow Limitations Instructor Notes Answers SA-26 - LEVEL III — Diagnosing a Severe Cabin Cooling Failure Instructor Notes Answers SA-27 - LEVEL III — Diagnosing a Cabin Heating Limitation Instructor Notes Answers Advanced Battery Flow Section Assessment Diagrams and Schematics Mode 1 = Cabin Cool : Heat Pump Mode 2 = Cabin Heat : Heat Pump Mode 3 = Cabin Heat + Defrost : Heat Pump Mode 4 = Cabin Heat : PTC + Glycol Radiator Mode 5 = Battery Cool : Glycol Radiator Mode 6 = Battery Cool : HVAC Mode 7 = Battery Heat : PTC + Glycol Mode 8 = Cabin Heat & Battery Cool : HVAC Mode 9 = Battery Cool : HVAC + Glycol Radiator Mode 10 = Cabin Cool + Battery Cool : HVAC + Glycol Radiator Blank Diagram With ID Fault Schematic Glossary
