AC SYSTEMS ASE REVIEW EXAM 150 QUESTIONS &
CORRECT ANSWERS LATEST 2025
During normal A/C operation a loud hissing noise is heard and a cloud of vapor is
discharged from under the vehicle. Tech A says that excessive high-side pressure
caused the pressure relief valve on the A/C compressor to trip may have been the
result of a defective engine cooling fan clutch. Tech B says that the relief valve
may have been tripped due to a defective shutter control solenoid. Who is right?
A. Technician A
B. Technician B
C. Both A and B
D. Neither A nor B - ANSWER-C. Both A and B
During a performance test, the A/C compressor clutch is observed to be slipping.
Tech A says that the air gap was probably set improperly. Tech B says that the
pressure plate needs to be resurfaced. Who is right?
A. Technician A
B. Technician B
C. Both A and B
D. Neither A nor B - ANSWER-A. Technician A
To check and adjust the A/C compressor lubricant level:
A. quickly purge the system and add oil charges to refill it
,B. open the drain plug and crank the engine until the compressor is empty, then
pump fresh oil into the compressor
C. remove the compressor from the vehicle, drain the oil, and add the specified
quantity of fresh oil
D. add refrigerant oil until you can see the oil level. - ANSWER-C. remove the
compressor from the vehicle, drain the oil, and add the specified quantity of fresh
oil
Refrigerant oil must be added to the new component prior to installation when
replacing any of the following EXCEPT:
A. the evaporator
B. the condenser
C. the accumulator
D. the suction throttling valve - ANSWER-D. the suction throttling valve
Airflow through the A/C condenser will be significantly affected by all of the
following EXCEPT:
A. debris trapped in the fins
B. relative humidity of outside air
C. bent cooling fins
D. vehicle speed - ANSWER-B. relative humidity of outside air
Technician A says that deformed or improperly aligned condenser mounting
insulators will damage the A/C compressor. Technician B says that deformed or
improperly aligned condenser mounting insulators could damage the condenser
and refrigerant lines. Who is correct?
A. Technician A
,B. Technician B
C. Both A and B
D. Neither A nor B - ANSWER-B. Technician B
Technician A says that whenever the A/C system has been open to atmosphere
for an extended time, the receiver/dryer should be replaced. Technician B says
that when a compressor is replaced, the receiver dryer should also be replaced.
Who is correct?
A. Tech A
B. Tech B
C. Both
D. Neither - ANSWER-C. Both
When attempting to verify a leaking evaporator core, the technician is LEAST-
likely to sense refrigerant with the detector probe:
A. at the evaporator case drain
B. over the expansion valve
C. at the panel vents
D. at the defroster vents - ANSWER-B. over the expansion valve
To remove a mildew odor from the A/C output air:
A. remove the evaporator case, clean it with a vinegar and water solution, and dry
it thoroughly before reinstallation
B. spray a disinfectant into the panel outlets
C. pour a small amount of alcohol into the air intake plenum
, D. place an automotive deodorizer under the dash - ANSWER-A. remove the
evaporator case, clean it with a vinegar and water solution, and dry it thoroughly
before reinstallation
Technician A says that the R-12 A/C service has a removable core. Technician B
says that the R-134a service valve must be rear seated during A/C compressor
replacement. Who is right?
A. A only
B. B only
C. Both
D. Neither - ANSWER-A. Tech A
The A/C high-pressure valve shows evidence of slight oil leakage. Technician A
says you must replace the valve and repair the leak. Technician B says that if the
valve is just leaking a little oil and not refrigerant, repair is not necessary. Who is
right?
A. Tech A
B. Tech B
C. Both
D. Neither - ANSWER-A. Tech A
With the HVAC system in DEFROST mode, the blower on HIGH, and the
temperature control on COLD, the bottom of the windshield fogs up on the
outside because:
A. the evaporator drain is clogged
B. the heater core leaks
C. the evaporator core is iced up
CORRECT ANSWERS LATEST 2025
During normal A/C operation a loud hissing noise is heard and a cloud of vapor is
discharged from under the vehicle. Tech A says that excessive high-side pressure
caused the pressure relief valve on the A/C compressor to trip may have been the
result of a defective engine cooling fan clutch. Tech B says that the relief valve
may have been tripped due to a defective shutter control solenoid. Who is right?
A. Technician A
B. Technician B
C. Both A and B
D. Neither A nor B - ANSWER-C. Both A and B
During a performance test, the A/C compressor clutch is observed to be slipping.
Tech A says that the air gap was probably set improperly. Tech B says that the
pressure plate needs to be resurfaced. Who is right?
A. Technician A
B. Technician B
C. Both A and B
D. Neither A nor B - ANSWER-A. Technician A
To check and adjust the A/C compressor lubricant level:
A. quickly purge the system and add oil charges to refill it
,B. open the drain plug and crank the engine until the compressor is empty, then
pump fresh oil into the compressor
C. remove the compressor from the vehicle, drain the oil, and add the specified
quantity of fresh oil
D. add refrigerant oil until you can see the oil level. - ANSWER-C. remove the
compressor from the vehicle, drain the oil, and add the specified quantity of fresh
oil
Refrigerant oil must be added to the new component prior to installation when
replacing any of the following EXCEPT:
A. the evaporator
B. the condenser
C. the accumulator
D. the suction throttling valve - ANSWER-D. the suction throttling valve
Airflow through the A/C condenser will be significantly affected by all of the
following EXCEPT:
A. debris trapped in the fins
B. relative humidity of outside air
C. bent cooling fins
D. vehicle speed - ANSWER-B. relative humidity of outside air
Technician A says that deformed or improperly aligned condenser mounting
insulators will damage the A/C compressor. Technician B says that deformed or
improperly aligned condenser mounting insulators could damage the condenser
and refrigerant lines. Who is correct?
A. Technician A
,B. Technician B
C. Both A and B
D. Neither A nor B - ANSWER-B. Technician B
Technician A says that whenever the A/C system has been open to atmosphere
for an extended time, the receiver/dryer should be replaced. Technician B says
that when a compressor is replaced, the receiver dryer should also be replaced.
Who is correct?
A. Tech A
B. Tech B
C. Both
D. Neither - ANSWER-C. Both
When attempting to verify a leaking evaporator core, the technician is LEAST-
likely to sense refrigerant with the detector probe:
A. at the evaporator case drain
B. over the expansion valve
C. at the panel vents
D. at the defroster vents - ANSWER-B. over the expansion valve
To remove a mildew odor from the A/C output air:
A. remove the evaporator case, clean it with a vinegar and water solution, and dry
it thoroughly before reinstallation
B. spray a disinfectant into the panel outlets
C. pour a small amount of alcohol into the air intake plenum
, D. place an automotive deodorizer under the dash - ANSWER-A. remove the
evaporator case, clean it with a vinegar and water solution, and dry it thoroughly
before reinstallation
Technician A says that the R-12 A/C service has a removable core. Technician B
says that the R-134a service valve must be rear seated during A/C compressor
replacement. Who is right?
A. A only
B. B only
C. Both
D. Neither - ANSWER-A. Tech A
The A/C high-pressure valve shows evidence of slight oil leakage. Technician A
says you must replace the valve and repair the leak. Technician B says that if the
valve is just leaking a little oil and not refrigerant, repair is not necessary. Who is
right?
A. Tech A
B. Tech B
C. Both
D. Neither - ANSWER-A. Tech A
With the HVAC system in DEFROST mode, the blower on HIGH, and the
temperature control on COLD, the bottom of the windshield fogs up on the
outside because:
A. the evaporator drain is clogged
B. the heater core leaks
C. the evaporator core is iced up
