AZ ROC – R-38 Air Conditioning &
Refrigeration Contractor Examination
Questions and Correct Answers (Verified
Answers) Plus Rationale 2027 Q&A| Instant
Download Pdf
1. What is the primary function of the evaporator in a vapor-
compression refrigeration system?
A. Reject heat to the outdoor air
B. Increase refrigerant pressure
C. Absorb heat from the conditioned space
D. Store liquid refrigerant
Rationale: The evaporator is the heat-absorbing component of the
refrigeration cycle. Low-pressure refrigerant enters the evaporator
and absorbs heat from indoor air or another medium as it changes
state from liquid to vapor.
,2. Which component raises the pressure and temperature of
refrigerant vapor before it enters the condenser?
A. Expansion valve
B. Evaporator
C. Receiver
D. Compressor
Rationale: The compressor takes low-pressure, low-temperature
vapor from the evaporator and compresses it into a high-pressure,
high-temperature vapor. This allows the refrigerant to reject heat
effectively in the condenser.
3. What is the primary purpose of the condenser?
A. Absorb heat from the building
B. Meter refrigerant into the evaporator
C. Reject heat from the refrigerant
D. Reduce compressor discharge pressure
Rationale: The condenser removes heat from the high-pressure
refrigerant vapor. As heat is rejected, the refrigerant condenses from
vapor into a liquid.
4. What is the primary purpose of a thermostatic expansion valve
(TXV)?
,A. Increase refrigerant pressure
B. Remove moisture from refrigerant
C. Meter refrigerant flow into the evaporator
D. Increase compressor capacity
Rationale: A TXV regulates the amount of refrigerant entering the
evaporator based largely on evaporator outlet superheat. Proper
metering helps maintain efficient evaporator operation and protects
the compressor from liquid refrigerant.
5. In an air-conditioning system, superheat is best described as:
A. The temperature of liquid refrigerant below its saturation
temperature
B. The temperature of vapor above its saturation temperature
C. The difference between outdoor and indoor temperature
D. The pressure difference across the compressor
Rationale: Superheat is sensible heating of a vapor above its
saturation temperature at a given pressure. Measuring superheat is
useful for evaluating evaporator performance and refrigerant charge.
6. Subcooling refers to:
A. Heating vapor above saturation temperature
B. Cooling the compressor below ambient temperature
, C. Cooling liquid refrigerant below its saturation temperature
D. Reducing airflow across the evaporator
Rationale: Subcooling occurs when liquid refrigerant is cooled below
its saturation temperature. Proper condenser subcooling helps ensure
that solid liquid refrigerant reaches the metering device.
7. What happens to refrigerant pressure as it passes through a typical
fixed expansion device?
A. It increases substantially
B. It remains exactly constant
C. It decreases
D. It becomes atmospheric
Rationale: The expansion device creates a pressure drop between the
high side and low side of the refrigeration system. The resulting lower
pressure permits part of the liquid refrigerant to flash into vapor and
lowers its temperature.
8. Which instrument is normally used to measure refrigerant
pressure?
A. Psychrometer
B. Clamp meter
Refrigeration Contractor Examination
Questions and Correct Answers (Verified
Answers) Plus Rationale 2027 Q&A| Instant
Download Pdf
1. What is the primary function of the evaporator in a vapor-
compression refrigeration system?
A. Reject heat to the outdoor air
B. Increase refrigerant pressure
C. Absorb heat from the conditioned space
D. Store liquid refrigerant
Rationale: The evaporator is the heat-absorbing component of the
refrigeration cycle. Low-pressure refrigerant enters the evaporator
and absorbs heat from indoor air or another medium as it changes
state from liquid to vapor.
,2. Which component raises the pressure and temperature of
refrigerant vapor before it enters the condenser?
A. Expansion valve
B. Evaporator
C. Receiver
D. Compressor
Rationale: The compressor takes low-pressure, low-temperature
vapor from the evaporator and compresses it into a high-pressure,
high-temperature vapor. This allows the refrigerant to reject heat
effectively in the condenser.
3. What is the primary purpose of the condenser?
A. Absorb heat from the building
B. Meter refrigerant into the evaporator
C. Reject heat from the refrigerant
D. Reduce compressor discharge pressure
Rationale: The condenser removes heat from the high-pressure
refrigerant vapor. As heat is rejected, the refrigerant condenses from
vapor into a liquid.
4. What is the primary purpose of a thermostatic expansion valve
(TXV)?
,A. Increase refrigerant pressure
B. Remove moisture from refrigerant
C. Meter refrigerant flow into the evaporator
D. Increase compressor capacity
Rationale: A TXV regulates the amount of refrigerant entering the
evaporator based largely on evaporator outlet superheat. Proper
metering helps maintain efficient evaporator operation and protects
the compressor from liquid refrigerant.
5. In an air-conditioning system, superheat is best described as:
A. The temperature of liquid refrigerant below its saturation
temperature
B. The temperature of vapor above its saturation temperature
C. The difference between outdoor and indoor temperature
D. The pressure difference across the compressor
Rationale: Superheat is sensible heating of a vapor above its
saturation temperature at a given pressure. Measuring superheat is
useful for evaluating evaporator performance and refrigerant charge.
6. Subcooling refers to:
A. Heating vapor above saturation temperature
B. Cooling the compressor below ambient temperature
, C. Cooling liquid refrigerant below its saturation temperature
D. Reducing airflow across the evaporator
Rationale: Subcooling occurs when liquid refrigerant is cooled below
its saturation temperature. Proper condenser subcooling helps ensure
that solid liquid refrigerant reaches the metering device.
7. What happens to refrigerant pressure as it passes through a typical
fixed expansion device?
A. It increases substantially
B. It remains exactly constant
C. It decreases
D. It becomes atmospheric
Rationale: The expansion device creates a pressure drop between the
high side and low side of the refrigeration system. The resulting lower
pressure permits part of the liquid refrigerant to flash into vapor and
lowers its temperature.
8. Which instrument is normally used to measure refrigerant
pressure?
A. Psychrometer
B. Clamp meter
