• 42 questions

T7 Heavy Duty AC ASE Practice Test

Unofficial practice for ASE's T7 test: heavy duty truck air conditioning, heating, engine cooling and HVAC controls.

A cab bracket is to be welded close to an A/C line. Why does the Navy manual forbid welding or excessive heat near the system or the refrigerant tanks?

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Exam mode: 40 questions, 60 minutes.

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Unofficial practice questions, not affiliated with the National Institute for Automotive Service Excellence (ASE). Bank checked October 14, 2026.

Next step Buses too: ASE H7 HVAC practice

All 42 questions

HVAC systems diagnosis 6

  • A cab bracket is to be welded close to an A/C line. Why does the Navy manual forbid welding or excessive heat near the system or the refrigerant tanks? US Navy NAVEDTRA 14050, Construction Mechanic, Advanced (1992), chapter 13, Refrigerant. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), A. HVAC Systems Diagnosis, Service, and Repair (6 of 40)
  • A driver reports poor cooling. By the Navy manual, which job makes up most air-conditioning service work? US Navy NAVEDTRA 14050, Construction Mechanic, Advanced (1992), chapter 13, Inspecting the Air-Conditioning System for Leaks. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), A. HVAC Systems Diagnosis, Service, and Repair (6 of 40)
  • A functional test is run to establish the condition of all components. What does the Navy manual require while the test is performed? US Navy NAVEDTRA 14050, Construction Mechanic, Advanced (1992), chapter 13, Functional Testing. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), A. HVAC Systems Diagnosis, Service, and Repair (6 of 40)
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HVAC systems diagnosis, continued

  • A large quantity of refrigerant escapes in a closed shop. Which hazard does the Navy manual name for the people in it? US Navy NAVEDTRA 14050, Construction Mechanic, Advanced (1992), chapter 13, Refrigerant. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), A. HVAC Systems Diagnosis, Service, and Repair (6 of 40)
  • During a performance check the driver closes the outside air flaps. What does recirculating cabin air do? Wikipedia, Automotive air conditioning, Operating principles. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), A. HVAC Systems Diagnosis, Service, and Repair (6 of 40)
  • Why does the Navy manual require rubber gloves and safety goggles when a charged refrigeration system is serviced? US Navy NAVEDTRA 14050, Construction Mechanic, Advanced (1992), chapter 13, Refrigerant. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), A. HVAC Systems Diagnosis, Service, and Repair (6 of 40)

A/C system and components 21

  • A compact compressor uses three double-ended pistons driven by a wobble plate. How many cylinders does that effectively give, by the Navy manual? US Navy NAVEDTRA 14050, Construction Mechanic, Advanced (1992), chapter 13, Six-Cylinder Axial Compressor. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), B. A/C System and Component Diagnosis, Service, and Repair (20 of 40)
  • A receiver/drier is saturated with moisture, or its filter is restricted. What does the Navy manual say to do? US Navy NAVEDTRA 14050, Construction Mechanic, Advanced (1992), chapter 13, Malfunctions of Components in the Air-Conditioning System, Receiver/Drier. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), B. A/C System and Component Diagnosis, Service, and Repair (20 of 40)
  • A sticker under the hood of a truck concerns leak detection. What does the Navy manual say such a sticker usually indicates? US Navy NAVEDTRA 14050, Construction Mechanic, Advanced (1992), chapter 13, Internally Charged Detector. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), B. A/C System and Component Diagnosis, Service, and Repair (20 of 40)
  • A system is charged from disposable cans. Which can valve does the Navy manual call for? US Navy NAVEDTRA 14050, Construction Mechanic, Advanced (1992), chapter 13, Handling Refrigerant. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), B. A/C System and Component Diagnosis, Service, and Repair (20 of 40)
  • A system is charged with vapor through the low side while it runs. What moves the refrigerant from the can into the system, by the Navy manual? US Navy NAVEDTRA 14050, Construction Mechanic, Advanced (1992), chapter 13, Purging the Air-Conditioning System. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), B. A/C System and Component Diagnosis, Service, and Repair (20 of 40)
  • A system is overcharged and moisture is present in it. What does the Navy manual say must be done? US Navy NAVEDTRA 14050, Construction Mechanic, Advanced (1992), chapter 13, Malfunctions of Components in the Air-Conditioning System, Compressor. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), B. A/C System and Component Diagnosis, Service, and Repair (20 of 40)
  • A truck A/C system uses an orifice tube. Technician A says its drier, called an accumulator, sits between the evaporator outlet and the compressor. Technician B says the accumulator keeps liquid refrigerant from reaching the compressor during low cooling demand. Who is right? Wikipedia, Automotive air conditioning, Operating principles. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), B. A/C System and Component Diagnosis, Service, and Repair (20 of 40)
  • A truck sits at idle and no air moves through the condenser by vehicle motion. What cools the condenser then? Wikipedia, Automotive air conditioning, Operating principles. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), B. A/C System and Component Diagnosis, Service, and Repair (20 of 40)
  • A warm evaporator raises the pressure in the thermal bulb of an expansion valve. How does that pressure reach the valve diaphragm, by the Navy manual? US Navy NAVEDTRA 14050, Construction Mechanic, Advanced (1992), chapter 13, Expansion Valve. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), B. A/C System and Component Diagnosis, Service, and Repair (20 of 40)
  • Airflow at the cab vents is weak, and heating and cooling are both poor. Which part is a known cause? Wikipedia, Air filter, Automotive cabin air filters, Performance. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), B. A/C System and Component Diagnosis, Service, and Repair (20 of 40)
  • An underhood label names R-134a as the refrigerant. What kind of refrigerant is R-134a? Wikipedia, Automotive air conditioning, R-134a. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), B. A/C System and Component Diagnosis, Service, and Repair (20 of 40)
  • How does system pressure change the boiling point of the refrigerant, by the Navy manual? US Navy NAVEDTRA 14050, Construction Mechanic, Advanced (1992), chapter 13, Pressure Temperature Relationship. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), B. A/C System and Component Diagnosis, Service, and Repair (20 of 40)
  • How does the electronic leak detector of the Navy manual show a refrigerant leak? US Navy NAVEDTRA 14050, Construction Mechanic, Advanced (1992), chapter 13, Electronic Detector. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), B. A/C System and Component Diagnosis, Service, and Repair (20 of 40)
  • How does the lubricant of the compressor travel in a vehicle A/C system? Wikipedia, Automotive air conditioning, Operating principles. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), B. A/C System and Component Diagnosis, Service, and Repair (20 of 40)
  • How does the Navy manual say refrigerant tanks are to be kept when they are not in use? US Navy NAVEDTRA 14050, Construction Mechanic, Advanced (1992), chapter 13, Handling Refrigerant. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), B. A/C System and Component Diagnosis, Service, and Repair (20 of 40)
  • How is the bubble detector of the Navy manual used to find a refrigerant leak? US Navy NAVEDTRA 14050, Construction Mechanic, Advanced (1992), chapter 13, Inspecting the Air-Conditioning System for Leaks. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), B. A/C System and Component Diagnosis, Service, and Repair (20 of 40)
  • In the two-cylinder reciprocating compressor of the Navy manual, what controls gas flow? US Navy NAVEDTRA 14050, Construction Mechanic, Advanced (1992), chapter 13, Two-Cylinder Reciprocating Compressor. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), B. A/C System and Component Diagnosis, Service, and Repair (20 of 40)
  • Water drips under the cab while the A/C runs. Where does that water come from, by the Navy manual? US Navy NAVEDTRA 14050, Construction Mechanic, Advanced (1992), chapter 13, The Evaporator. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), B. A/C System and Component Diagnosis, Service, and Repair (20 of 40)
  • What does the pumping action of the compressor do to the refrigerant, by the Navy manual? US Navy NAVEDTRA 14050, Construction Mechanic, Advanced (1992), chapter 13, Refrigeration Cycle. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), B. A/C System and Component Diagnosis, Service, and Repair (20 of 40)
  • While the system is searched for leaks, which other items does the Navy manual tell the technician to check at the same time? US Navy NAVEDTRA 14050, Construction Mechanic, Advanced (1992), chapter 13, Inspecting the Air-Conditioning System for Leaks. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), B. A/C System and Component Diagnosis, Service, and Repair (20 of 40)
  • Why must the receiver-drier remove residual water from the refrigerant and oil? Wikipedia, Automotive air conditioning, Operating principles. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), B. A/C System and Component Diagnosis, Service, and Repair (20 of 40)

Heating and engine cooling 7

  • A coolant overflow tank is found dry. What may that lead to? Wikipedia, Radiator (engine cooling), Boiling or overheating. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), C. Heating and Engine Cooling Systems Diagnosis, Service, and Repair (6 of 40)
  • A fuel-fired coolant heater warms a parked truck. How much fuel do coolant heaters burn compared with an idling engine, by the Wikipedia article on idle reduction? Wikipedia, Idle reduction, Fuel-operated coolant heaters. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), C. Heating and Engine Cooling Systems Diagnosis, Service, and Repair (6 of 40)
  • A radiator cap for a pressurized cooling system has two valves. What do they do? Wikipedia, Radiator (engine cooling), Pressurized cooling systems. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), C. Heating and Engine Cooling Systems Diagnosis, Service, and Repair (6 of 40)
  • An electric cooling fan loses some energy in converting engine power to electricity and back. What more than makes up for that loss? Wikipedia, Fan clutch, Function. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), C. Heating and Engine Cooling Systems Diagnosis, Service, and Repair (6 of 40)
  • How does a thermostatic fan clutch behave when the engine is cold? Wikipedia, Fan clutch, lead section. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), C. Heating and Engine Cooling Systems Diagnosis, Service, and Repair (6 of 40)
  • Vent air is too cold on a mild day. How is cooled air brought back up to the selected temperature? Wikipedia, Automotive air conditioning, Operating principles. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), C. Heating and Engine Cooling Systems Diagnosis, Service, and Repair (6 of 40)
  • Which glycol is frequently used as a substitute for ethylene glycol in low toxicity antifreeze? Wikipedia, Propylene glycol, Antifreeze. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), C. Heating and Engine Cooling Systems Diagnosis, Service, and Repair (6 of 40)

Operating systems and controls 8

  • A blower motor runs slowly, and a meter shows voltage lost across a corroded connector. What is voltage drop? Wikipedia, Voltage drop, lead section. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), D. Operating Systems and Related Controls Diagnosis and Repair (8 of 40)
  • A compressor clutch relay is tested. What is a relay? Wikipedia, Relay, lead section. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), D. Operating Systems and Related Controls Diagnosis and Repair (8 of 40)
  • A control module regulates blower speed precisely to adjust air temperature. What is the aim? Wikipedia, Automotive air conditioning, Operating principles. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), D. Operating Systems and Related Controls Diagnosis and Repair (8 of 40)
  • A sleeper cab has an inverter for its HVAC accessories. What does a power inverter do? Wikipedia, Power inverter, lead section. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), D. Operating Systems and Related Controls Diagnosis and Repair (8 of 40)
  • An automatic temperature control commands a variable displacement compressor. How does reduced displacement serve the control system? Wikipedia, Automotive air conditioning, Operating principles. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), D. Operating Systems and Related Controls Diagnosis and Repair (8 of 40)
  • An inverter-fed HVAC load keeps shutting down. Where does the power that an inverter delivers come from? Wikipedia, Power inverter, lead section. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), D. Operating Systems and Related Controls Diagnosis and Repair (8 of 40)
  • How does an electromagnetic compressor clutch operate and transmit torque? Wikipedia, Electromagnetic clutch, lead section. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), D. Operating Systems and Related Controls Diagnosis and Repair (8 of 40)
  • What is an auxiliary power unit (APU) commonly used for on a semi-truck? Wikipedia, Idle reduction, Auxiliary power units. Outline: ASE Medium/Heavy Truck Study Guide (2026), HVAC Systems (Test T7), D. Operating Systems and Related Controls Diagnosis and Repair (8 of 40)

How this list was compiled: Our own questions, written to the four content areas of the Heating, Ventilation, and Air Conditioning (HVAC) Systems (Test T7) test specifications and task list in the ASE Medium/Heavy Truck Study Guide (copyright 2026, https://ase.com/wp-content/uploads/ASE_MedHeavyTruck_Study_Guide.pdf, read 2026-10-14): A HVAC systems diagnosis, service and repair 6 of 40 scored questions, B A/C system and component diagnosis, service and repair 20, C heating and engine cooling systems 6, D operating systems and related controls 8. The bank holds 6, 21, 7 and 8. Every fact was read on 2026-10-14 in the public text the question names: US Navy NAVEDTRA 14050, Construction Mechanic, Advanced (1992), chapter 13, in the copy at archive.org; and Wikipedia articles on automotive air conditioning, air filters, radiators, the fan clutch, propylene glycol, idle reduction, power inverters, relays, electromagnetic clutches and voltage drop. The sample questions printed in the study guide were not used. Licence: Questions, choices and explanations are original work of this site. NAVEDTRA 14050 is a work of the United States Navy approved for public release, and no question or example is copied from it.

How it works

This T7 heavy duty AC ASE practice test asks 42 questions on truck air conditioning, heating and controls. It is free and unofficial: the National Institute for Automotive Service Excellence (ASE) does not sponsor or endorse it.

Read the full guide

Half of T7 is the A/C system

ASE's Medium/Heavy Truck study guide gives A/C system and component diagnosis 20 of the 40 scored questions. Operating systems and controls have 8, HVAC systems diagnosis 6, and heating and engine cooling 6. Sleeper units, auxiliary power units and shore power are on the task list.

Where the HVAC answers come from

Refrigerant handling, leak finding, compressor and expansion valve questions rest on a Navy mechanic's manual from the years R-134a replaced R-12. Accumulators, cabin filters, coolant, fans and idle reduction rest on Wikipedia. Scan tool screens are not asked.

T7 is not a Section 609 card

ASE's guide says its HVAC certifications, T7 among them, do not satisfy EPA's Section 609 refrigerant requirements. That takes a separate program, whose rules the EPA 609 practice test here asks.

  • Learn the path of the refrigerant first: compressor, condenser, receiver-drier, expansion valve, evaporator. Most A/C questions follow from it.

Questions and answers

How many questions are on the ASE T7 test?

Fifty, by ASE's 2026 Medium/Heavy Truck study guide: 40 scored and 10 that are not counted, in 60 minutes. The recertification test is 20 questions in 30 minutes.

Is there a free ASE certification practice test for T7?

This page is one. It costs nothing and needs no account, and the questions can be printed with an answer key. They were written for this site and are not ASE's.

Is this an ASE T7 study guide?

ASE publishes the official one free: the Medium/Heavy Truck study guide, with the T7 task list and seven sample questions. This page is practice on that task list, each answer tied to a public source you can open.

Does T7 cover the sleeper and the APU?

Yes. The T7 task list names cab and sleeper expansion valves and evaporators, and the diagnosis of auxiliary power unit, inverter and shore power HVAC controls.

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