Ten ASE A7 Heating & Air Conditioning questions in the ASE format: four options, one best answer. They are free to use, print and share, and there is nothing to sign up for on this page.
01How to use these
The questions come from the ToolboxPrep A7 bank and are spread across the test's content areas in the proportion the ASE test specification gives them: A (Heating, Ventilation, A/C (HVAC), and Engine Cooling System Service, Diagnosis, and Repair), B (Refrigeration System Component Diagnosis and Repair), C (Operating Systems and Related Controls Diagnosis and Repair). Answer each one before opening the explanation. Every explanation covers all four options, because knowing why the wrong answers are wrong is most of the skill.
- Pace. The A7 test gives you 75 minutes for 60 questions (50 scored, 10 unscored), about 1 min 15 s a question. Try these at that pace.
- Print. The printed version shows the questions and the answer key without the explanations, so it works as a handout.
02The questions
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Which of these features identifies a climate control system as automatic temperature control (ATC) rather than manual?
- It moves its blend door with an electric actuator
- Its blower speed is set by a control module
- It holds a set cabin temperature using sensors
- It has separate driver and passenger zones
Show the answer
C. Correct. An ATC system takes a temperature setting and uses in-car, ambient and often sun-load sensors to adjust the blend, blower speed and mode on its own to hold it. A manual system only moves its doors and blower to where the driver sets them, even when the doors are moved electrically.
Why not the others
A. Many manual systems also use electric blend-door actuators driven from the control knob, so the actuator does not make a system automatic.
B. Manual systems can use a blower speed control module too; what makes a system automatic is temperature control from sensors.
D. Dual-zone systems can be manual or automatic; zones describe how many temperatures the system controls, not how it controls them.
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A vehicle's A/C label was lost when its hood was replaced, and the system is empty after a condenser replacement. Where should the technician get the refrigerant charge amount?
- The amount the machine recovered
- The service information for that vehicle
- The pressure chart, charging until it matches
- The compressor's identification label
Show the answer
B. Correct. The charge is set for each vehicle's system and is published in its service information as well as on the label, so that is the source when the label is gone. The system is then charged by weight to that figure, and a replacement label can be ordered.
Why not the others
A. The system may have been leaking before the repair, so what came out says nothing about what it should hold.
C. Pressures vary with ambient temperature, humidity and airflow and can look normal across a range of charges, so they cannot set the amount.
D. A compressor's label identifies the compressor, not the system; the refrigerant charge depends on the whole system, its condenser, evaporator, lines and any rear unit, so it is found in the vehicle's service information.
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The recycling process of an approved R-134a recovery/recycling/recharging machine is built to remove any of these from the refrigerant it recovers EXCEPT:
- moisture picked up in the vehicle's system.
- a second refrigerant mixed into the charge.
- air and other noncondensable gases.
- refrigerant oil carried out with the refrigerant.
Show the answer
B. Correct. Recycling cleans moisture, oil and air out of one refrigerant; it cannot separate two refrigerants that have been mixed. That is why the refrigerant is identified before recovery, so a charge that fails the identifier's purity check never enters the recycling machine's tank.
Why not the others
A. The machine's filter-drier traps moisture, which would otherwise freeze at the expansion device and form acids. Removing it is a core part of recycling, and the machine signals when the filter must be changed.
C. Noncondensable gases, mainly air, collect in the machine's tank and are purged by the machine. Their removal is built into normal recycling operation.
D. The machine separates the oil from the recovered refrigerant and measures it, so the technician knows how much oil to put back. Oil removal is part of the recycling process.
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A pressure tester replaces the radiator cap on a cold engine and is pumped to the cap's rated 16 psi. In 10 minutes the gauge falls to 6 psi, but no coolant can be seen leaking under the hood, under the vehicle or in the passenger compartment. Any of these could explain the drop EXCEPT:
- a head gasket leaking coolant into a cylinder.
- a cracked combustion chamber in the cylinder head.
- a coolant-type oil cooler leaking into the oil.
- a cap relief valve that opens too early.
Show the answer
D. Correct. The tester is fitted in place of the cap, so the cap is not part of the system being pressurized and cannot let the gauge fall. The cap is tested separately on an adapter; this drop with no external leak points to an internal leak.
Why not the others
A. A head gasket breach into a cylinder lets pressurized coolant seep into the combustion chamber, where it cannot be seen from outside. It could explain the drop; a cylinder leakage test or plug inspection follows.
B. A crack into a combustion chamber or port lets coolant leave the system inside the engine, with nothing visible outside. It could explain the drop.
C. With the engine off, there is no oil pressure, so a leaking coolant-type oil cooler lets pressurized coolant pass into the oil, out of sight. It could explain the drop, and the oil is checked for coolant.
-
The low-pressure switch on a vehicle's A/C system threads onto a fitting that has a valve core inside it. What does that core do when the switch is unscrewed?
- It meters a slow bleed so the pressure falls safely
- It closes and keeps the refrigerant in the system
- It damps pressure pulses so the switch reads steadily
- It blocks oil from collecting inside the switch
Show the answer
B. Correct. A pin in the switch holds the core open while the switch is installed, so the switch senses system pressure; as the switch is unscrewed, the core's spring closes it and holds the charge in. That is why the manufacturer may allow this kind of switch to be replaced without recovering the refrigerant, with a new O-ring or seal on the replacement.
Why not the others
A. A valve core does not meter a bleed; it is either held open or closed. When the switch comes off, the core's spring closes it and keeps the charge in the system.
C. The core is simply held open by the installed switch and does nothing to smooth pressure pulses. Its purpose shows when the switch is removed: it closes and holds the refrigerant in.
D. The core does not filter or block oil; with the switch installed it is held fully open. Its job is to close and hold the charge in when the switch is unscrewed.
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In a working A/C condenser, what happens to the refrigerant?
- Low-pressure vapor is squeezed into hot high-pressure vapor
- Low-pressure liquid absorbs heat and turns to vapor
- High-pressure liquid drops in pressure and cools
- High-pressure vapor gives off heat and turns to liquid
Show the answer
D. Correct. Hot, high-pressure vapor from the compressor gives up heat to the air passing through the condenser and condenses into high-pressure liquid, usually cooled slightly below its condensing temperature before it leaves. That liquid then goes on to the metering device.
Why not the others
A. That is the compressor's job. The condenser receives that hot vapor and removes heat from it until it condenses into liquid.
B. That is what happens in the evaporator, after the metering device, where the refrigerant absorbs heat from the cabin air. In the condenser, high-pressure vapor gives off heat and condenses.
C. The pressure drop happens at the expansion valve or orifice tube. In the condenser the refrigerant stays at high pressure as the vapor gives up heat and turns to liquid.
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Any of these is an accepted way to test an HVAC electrical circuit EXCEPT:
- checking a removed relay's coil resistance with an ohmmeter.
- back-probing a plugged-in connector with a DMM while the circuit operates.
- bypassing a switch with a fused jumper to see whether the load runs.
- probing a module's sensor signal wire with an incandescent test light.
Show the answer
D. Correct. An incandescent test light draws far more current than a module's sensor circuit is built to supply, so it loads the signal until the result means nothing and risks damaging the module's circuit. Service information calls for a high-impedance DMM, 10 megohms or more, on circuits with solid-state modules.
Why not the others
A. This is accepted: with the relay out of the circuit, an ohmmeter across its coil terminals shows an open or shorted coil against the manufacturer's specification.
B. This is accepted: reading voltage at the back of a plugged-in connector with the circuit working shows the real values under load without spreading the terminals or breaking the seals.
C. This is accepted: a fused jumper across a switch in a power circuit shows whether the load works with the switch out of the way, and the fuse protects the wiring if the load side is shorted.
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With the A/C on, a vehicle's electric condenser fan does not run, though the scan tool shows the PCM commanding it on. The PCM grounds the fan relay's coil, and the relay's contacts feed the motor through a fuse. Any of these could be the cause EXCEPT:
- a blown fuse feeding the relay's contacts.
- a failed PCM driver for the relay's coil.
- a pressure transducer reading low.
- an open in the relay coil's power feed.
Show the answer
C. Correct. The transducer is an input the PCM uses to decide when the fan should run, and the scan tool already shows the PCM commanding the fan on, so that decision has been made. The fault lies after the command: the PCM's output driver, the relay, its feeds, the fuse, the wiring or the motor.
Why not the others
A. This could cause it: with that fuse open, the relay's contacts have no power to pass to the motor however the PCM commands the relay.
B. This could cause it: the scan tool shows what the PCM is commanding, not whether its output transistor actually grounds the coil, so a driver that has failed open leaves the relay off despite the command.
D. This could cause it: the PCM's ground on the coil does nothing if the coil's feed is open, so the relay never closes despite the command.
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The foam seal on a heater case's defroster door has crumbled away. Which symptom would this cause?
- Some air leaking from the defroster in panel mode
- Warm air from the vents with the control at full cold
- Weak airflow only when recirculation is selected
- No airflow from any outlet on the lowest blower speed
Show the answer
A. Correct. A mode door seals its outlet with foam when it is closed; with the foam gone, some air slips past the closed defroster door, so air comes from the windshield outlets even in panel mode. The door's actuator and controls are working; the seal is what needs repair.
Why not the others
B. With the A/C working, warm air at full cold points to air leaking past the blend door, which controls air through the heater core. The defroster door only directs where the air leaves the case.
C. Recirculation airflow depends on the fresh/recirculation door at the case inlet. A defroster door seal affects where air goes out, not how much comes in.
D. Loss of the lowest speed is a blower control fault, such as a resistor or module. A door seal does not stop airflow.
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An in-car temperature sensor sits behind a small grille in the dash, with an aspirator tube (or a small fan) attached to its housing. What does the aspirator do?
- Blows outlet air onto the sensor
- Pulls cabin air across the sensor
- Cools the sensor's electronics
- Pushes dust out through the grille
Show the answer
B. Correct. The aspirator draws a small, steady stream of cabin air through the grille and past the sensor, so it reads the real cabin temperature rather than still air trapped behind the dash. A loose tube or stopped fan makes the reading lag or drift; a strip of tissue held at the grille should be drawn in.
Why not the others
A. Conditioned outlet air blown on the in-car sensor would make it read the duct temperature, not the cabin's. The aspirator pulls cabin air in through the grille instead.
C. The sensor is a simple thermistor that needs no cooling. The aspirator's job is to move cabin air across it so it reads the cabin accurately.
D. The airflow runs inward through the grille, not outward, and it is there for an accurate reading, not cleaning. A clogged grille weakens the aspirator's draw.
03Answer key
| Question | Answer | Content area |
|---|---|---|
| Q1 | C | Heating, Ventilation, A/C (HVAC), and Engine Cooling System Service, Diagnosis, and Repair |
| Q2 | B | Heating, Ventilation, A/C (HVAC), and Engine Cooling System Service, Diagnosis, and Repair |
| Q3 | B | Heating, Ventilation, A/C (HVAC), and Engine Cooling System Service, Diagnosis, and Repair |
| Q4 | D | Heating, Ventilation, A/C (HVAC), and Engine Cooling System Service, Diagnosis, and Repair |
| Q5 | B | Refrigeration System Component Diagnosis and Repair |
| Q6 | D | Refrigeration System Component Diagnosis and Repair |
| Q7 | D | Operating Systems and Related Controls Diagnosis and Repair |
| Q8 | C | Operating Systems and Related Controls Diagnosis and Repair |
| Q9 | A | Operating Systems and Related Controls Diagnosis and Repair |
| Q10 | B | Operating Systems and Related Controls Diagnosis and Repair |
04Questions by content area
Working on one part of the A7 test? Each content area has its own page with five more free questions.
05More free questions
The A7 study guide covers each content area and how to study for it, and the ASE A7 Heating & Air Conditioning practice test page describes the full A7 question bank. The same free format is available for the other eight tests.
How these questions are written and checked: how our questions are made. Found a mistake? Tell us and we will fix it.
ToolboxPrep is an independent study site. It is not affiliated with or endorsed by ASE (the National Institute for Automotive Service Excellence). Our questions are original practice questions written to the published ASE test specifications; they are not actual test questions.