CO HVAC Contractor Exam Questions
and Correct Answers (Verified Answers)
Plus Rationale 2027 Q&A| Instant
Download Pdf
1. What is the primary purpose of a refrigeration system in an HVAC
application?
A. To increase indoor humidity
B. To transfer heat from one location to another
C. To generate electrical power
D. To increase atmospheric pressure
Answer: B. To transfer heat from one location to another
Rationale: A refrigeration system does not create cold directly. It
removes heat from a space or substance and transfers that heat to
another location, typically outdoors.
, 2. Which component of a vapor-compression refrigeration system
raises the pressure and temperature of the refrigerant vapor?
A. Evaporator
B. Condenser
C. Compressor
D. Expansion valve
Answer: C. Compressor
Rationale: The compressor takes low-pressure refrigerant vapor from
the evaporator and compresses it into a high-pressure, high-
temperature vapor before it enters the condenser.
3. What is the primary function of the condenser?
A. Absorb heat from the conditioned space
B. Remove heat from the refrigerant
C. Reduce refrigerant pressure
D. Meter refrigerant into the evaporator
Answer: B. Remove heat from the refrigerant
Rationale: In the condenser, high-pressure refrigerant vapor releases
heat to the surrounding air or water and changes into a high-pressure
liquid.
, 4. What is the primary function of an evaporator coil?
A. Reject heat to outdoor air
B. Compress refrigerant vapor
C. Absorb heat from the conditioned space
D. Increase refrigerant pressure
Answer: C. Absorb heat from the conditioned space
Rationale: The evaporator is the heat-absorbing portion of the
refrigeration cycle. Refrigerant evaporates inside the coil as it absorbs
heat from air or another medium.
5. Which device meters refrigerant into the evaporator?
A. Compressor
B. Expansion device
C. Condenser fan
D. Receiver
Answer: B. Expansion device
Rationale: A metering or expansion device controls the amount of
refrigerant entering the evaporator while producing the pressure drop
needed for evaporation.
6. What happens to refrigerant pressure as it passes through a
typical expansion valve?
, A. It increases significantly
B. It remains constant
C. It decreases significantly
D. It becomes atmospheric pressure
Answer: C. It decreases significantly
Rationale: The expansion device creates a pressure drop between the
high-pressure liquid side and the low-pressure evaporator side.
7. What is superheat?
A. The temperature of saturated liquid above its boiling point
B. The temperature of vapor above its saturation temperature
C. The temperature of the condenser below ambient
D. The pressure difference between the suction and discharge
sides
Answer: B. The temperature of vapor above its saturation
temperature
Rationale: Superheat is the amount by which a vapor's actual
temperature exceeds its saturation temperature at a given pressure.
Proper superheat helps ensure that liquid refrigerant does not reach
the compressor.
and Correct Answers (Verified Answers)
Plus Rationale 2027 Q&A| Instant
Download Pdf
1. What is the primary purpose of a refrigeration system in an HVAC
application?
A. To increase indoor humidity
B. To transfer heat from one location to another
C. To generate electrical power
D. To increase atmospheric pressure
Answer: B. To transfer heat from one location to another
Rationale: A refrigeration system does not create cold directly. It
removes heat from a space or substance and transfers that heat to
another location, typically outdoors.
, 2. Which component of a vapor-compression refrigeration system
raises the pressure and temperature of the refrigerant vapor?
A. Evaporator
B. Condenser
C. Compressor
D. Expansion valve
Answer: C. Compressor
Rationale: The compressor takes low-pressure refrigerant vapor from
the evaporator and compresses it into a high-pressure, high-
temperature vapor before it enters the condenser.
3. What is the primary function of the condenser?
A. Absorb heat from the conditioned space
B. Remove heat from the refrigerant
C. Reduce refrigerant pressure
D. Meter refrigerant into the evaporator
Answer: B. Remove heat from the refrigerant
Rationale: In the condenser, high-pressure refrigerant vapor releases
heat to the surrounding air or water and changes into a high-pressure
liquid.
, 4. What is the primary function of an evaporator coil?
A. Reject heat to outdoor air
B. Compress refrigerant vapor
C. Absorb heat from the conditioned space
D. Increase refrigerant pressure
Answer: C. Absorb heat from the conditioned space
Rationale: The evaporator is the heat-absorbing portion of the
refrigeration cycle. Refrigerant evaporates inside the coil as it absorbs
heat from air or another medium.
5. Which device meters refrigerant into the evaporator?
A. Compressor
B. Expansion device
C. Condenser fan
D. Receiver
Answer: B. Expansion device
Rationale: A metering or expansion device controls the amount of
refrigerant entering the evaporator while producing the pressure drop
needed for evaporation.
6. What happens to refrigerant pressure as it passes through a
typical expansion valve?
, A. It increases significantly
B. It remains constant
C. It decreases significantly
D. It becomes atmospheric pressure
Answer: C. It decreases significantly
Rationale: The expansion device creates a pressure drop between the
high-pressure liquid side and the low-pressure evaporator side.
7. What is superheat?
A. The temperature of saturated liquid above its boiling point
B. The temperature of vapor above its saturation temperature
C. The temperature of the condenser below ambient
D. The pressure difference between the suction and discharge
sides
Answer: B. The temperature of vapor above its saturation
temperature
Rationale: Superheat is the amount by which a vapor's actual
temperature exceeds its saturation temperature at a given pressure.
Proper superheat helps ensure that liquid refrigerant does not reach
the compressor.
