Arizona C-39 Air Conditioning
& Refrigeration Contractor
Practice Exam | Questions,
Verified Answers & Detailed
Rationales | Complete
Contractor License Exam Prep
Study Guide | Updated 2026
Refrigeration
1. Which component raises the pressure and temperature of
refrigerant vapor in a basic vapor-compression system?
A. Evaporator
B. Condenser
C. Compressor
D. Expansion valve
Correct Answer: Compressor
Rationale: The compressor takes low-pressure vapor
from the evaporator and compresses it into a high-
pressure, high-temperature vapor before it enters the
condenser.
2. What is the primary function of the evaporator?
A. Reject heat to outdoor air
B. Absorb heat from the conditioned space or product
C. Increase refrigerant pressure
D. Store liquid refrigerant
Correct Answer: Absorb heat from the conditioned space
or product
,Rationale: The evaporator is the heat-absorbing portion
of the refrigeration cycle. Refrigerant boils inside the
evaporator while absorbing heat from the surrounding
air or product.
3. What is the primary purpose of the condenser?
A. Absorb indoor heat
B. Lower refrigerant pressure
C. Reject heat from the refrigerant
D. Meter liquid refrigerant
Correct Answer: Reject heat from the refrigerant
Rationale: The condenser removes heat from the high-
pressure refrigerant vapor, causing it to condense into a
high-pressure liquid.
4. What does a thermostatic expansion valve primarily
control?
A. Compressor speed
B. Refrigerant flow into the evaporator
C. Condenser fan speed
D. Condenser pressure
Correct Answer: Refrigerant flow into the evaporator
Rationale: A TXV meters refrigerant into the evaporator
to maintain the desired evaporator outlet superheat.
5. What condition generally results when excessive liquid
refrigerant returns to a reciprocating compressor?
A. Oil foaming only
B. Liquid slugging
C. Increased superheat
D. Reduced condenser pressure
Correct Answer: Liquid slugging
Rationale: Compressors are designed to compress
vapor, not liquid. Liquid entering the compressor can
,damage valves, pistons, connecting rods, or other
components.
6. What is superheat?
A. Temperature of liquid below saturation
B. Temperature of vapor above its saturation temperature
C. Pressure of saturated liquid
D. Temperature of the condenser below ambient
Correct Answer: Temperature of vapor above its
saturation temperature
Rationale: Superheat is the number of degrees a vapor
has been heated above its saturation temperature at a
given pressure.
7. What is subcooling?
A. Cooling vapor below its saturation temperature
B. Heating liquid above saturation
C. Cooling liquid below its saturation temperature
D. Increasing evaporator temperature
Correct Answer: Cooling liquid below its saturation
temperature
Rationale: Subcooling is the temperature difference
between the liquid refrigerant's saturation temperature
and its actual liquid temperature.
8. What is the main purpose of a liquid receiver?
A. Store excess liquid refrigerant
B. Remove moisture from air
C. Increase suction pressure
D. Replace the compressor
Correct Answer: Store excess liquid refrigerant
Rationale: A receiver provides a storage location for
liquid refrigerant, particularly in systems where
refrigerant charge or operating conditions vary.
, 9. What component is specifically designed to remove
moisture and certain contaminants from a refrigeration
system?
A. Accumulator
B. Filter-drier
C. Receiver
D. Sight glass
Correct Answer: Filter-drier
Rationale: A filter-drier removes moisture and filters
contaminants from the refrigerant circuit, helping
protect the expansion device and compressor.
10. What is a common indication of excessive non-
condensable gases in a refrigeration system?
A. Abnormally high head pressure
B. Extremely low condensing pressure
C. Zero superheat
D. Low ambient temperature
Correct Answer: Abnormally high head pressure
Rationale: Air and other non-condensables occupy
condenser volume and interfere with heat transfer,
commonly causing elevated condensing pressure and
temperature.
11. What is the preferred method for removing moisture
and non-condensables from a newly installed refrigerant
circuit before charging?
A. Purge with oxygen
B. Pull an appropriate vacuum with a vacuum pump
C. Open the service valve to atmosphere
D. Add extra refrigerant
Correct Answer: Pull an appropriate vacuum with a
vacuum pump
& Refrigeration Contractor
Practice Exam | Questions,
Verified Answers & Detailed
Rationales | Complete
Contractor License Exam Prep
Study Guide | Updated 2026
Refrigeration
1. Which component raises the pressure and temperature of
refrigerant vapor in a basic vapor-compression system?
A. Evaporator
B. Condenser
C. Compressor
D. Expansion valve
Correct Answer: Compressor
Rationale: The compressor takes low-pressure vapor
from the evaporator and compresses it into a high-
pressure, high-temperature vapor before it enters the
condenser.
2. What is the primary function of the evaporator?
A. Reject heat to outdoor air
B. Absorb heat from the conditioned space or product
C. Increase refrigerant pressure
D. Store liquid refrigerant
Correct Answer: Absorb heat from the conditioned space
or product
,Rationale: The evaporator is the heat-absorbing portion
of the refrigeration cycle. Refrigerant boils inside the
evaporator while absorbing heat from the surrounding
air or product.
3. What is the primary purpose of the condenser?
A. Absorb indoor heat
B. Lower refrigerant pressure
C. Reject heat from the refrigerant
D. Meter liquid refrigerant
Correct Answer: Reject heat from the refrigerant
Rationale: The condenser removes heat from the high-
pressure refrigerant vapor, causing it to condense into a
high-pressure liquid.
4. What does a thermostatic expansion valve primarily
control?
A. Compressor speed
B. Refrigerant flow into the evaporator
C. Condenser fan speed
D. Condenser pressure
Correct Answer: Refrigerant flow into the evaporator
Rationale: A TXV meters refrigerant into the evaporator
to maintain the desired evaporator outlet superheat.
5. What condition generally results when excessive liquid
refrigerant returns to a reciprocating compressor?
A. Oil foaming only
B. Liquid slugging
C. Increased superheat
D. Reduced condenser pressure
Correct Answer: Liquid slugging
Rationale: Compressors are designed to compress
vapor, not liquid. Liquid entering the compressor can
,damage valves, pistons, connecting rods, or other
components.
6. What is superheat?
A. Temperature of liquid below saturation
B. Temperature of vapor above its saturation temperature
C. Pressure of saturated liquid
D. Temperature of the condenser below ambient
Correct Answer: Temperature of vapor above its
saturation temperature
Rationale: Superheat is the number of degrees a vapor
has been heated above its saturation temperature at a
given pressure.
7. What is subcooling?
A. Cooling vapor below its saturation temperature
B. Heating liquid above saturation
C. Cooling liquid below its saturation temperature
D. Increasing evaporator temperature
Correct Answer: Cooling liquid below its saturation
temperature
Rationale: Subcooling is the temperature difference
between the liquid refrigerant's saturation temperature
and its actual liquid temperature.
8. What is the main purpose of a liquid receiver?
A. Store excess liquid refrigerant
B. Remove moisture from air
C. Increase suction pressure
D. Replace the compressor
Correct Answer: Store excess liquid refrigerant
Rationale: A receiver provides a storage location for
liquid refrigerant, particularly in systems where
refrigerant charge or operating conditions vary.
, 9. What component is specifically designed to remove
moisture and certain contaminants from a refrigeration
system?
A. Accumulator
B. Filter-drier
C. Receiver
D. Sight glass
Correct Answer: Filter-drier
Rationale: A filter-drier removes moisture and filters
contaminants from the refrigerant circuit, helping
protect the expansion device and compressor.
10. What is a common indication of excessive non-
condensable gases in a refrigeration system?
A. Abnormally high head pressure
B. Extremely low condensing pressure
C. Zero superheat
D. Low ambient temperature
Correct Answer: Abnormally high head pressure
Rationale: Air and other non-condensables occupy
condenser volume and interfere with heat transfer,
commonly causing elevated condensing pressure and
temperature.
11. What is the preferred method for removing moisture
and non-condensables from a newly installed refrigerant
circuit before charging?
A. Purge with oxygen
B. Pull an appropriate vacuum with a vacuum pump
C. Open the service valve to atmosphere
D. Add extra refrigerant
Correct Answer: Pull an appropriate vacuum with a
vacuum pump
