NASCLA Accredited Trade
Examination for HVAC Contractors
Exam Practice Questions And Correct
Answers (Verified Answers) Plus
Rationales 2027 Q&A | Instant
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1. Which component of a conventional vapor-compression HVAC system
absorbs heat from the conditioned space?
A. Condenser
B. Evaporator
C. Compressor
D. Receiver
,Rationale: The evaporator absorbs heat from the conditioned space as
refrigerant changes from a low-pressure liquid-vapor mixture toward
vapor. This heat absorption is the fundamental cooling process.
2. What is the primary function of the compressor in a vaporcompression
refrigeration system?
A. To remove moisture from indoor air
B. To reject heat directly to the conditioned space
C. To raise the pressure and temperature of refrigerant vapor and circulate
refrigerant through the system
D. To convert liquid refrigerant directly into ice
Rationale: The compressor draws in low-pressure refrigerant vapor from
the evaporator and compresses it into a higher-pressure,
highertemperature vapor that can reject heat in the condenser.
3. What is the primary function of the condenser in an air-conditioning
system?
A. To absorb heat from the conditioned space
B. To reject heat from the refrigerant to the surrounding environment
C. To lower indoor humidity exclusively
,D. To meter refrigerant into the evaporator
Rationale: The condenser removes heat from the high-pressure refrigerant
vapor and rejects that heat to outdoor air or another heat sink. The
refrigerant normally condenses into a liquid during this process.
4. What is the primary purpose of a metering device such as a
thermostatic expansion valve?
A. To increase refrigerant pressure before the compressor
B. To remove heat from the condenser
C. To regulate refrigerant flow into the evaporator and produce the
necessary pressure drop
D. To circulate condenser air
Rationale: The metering device controls refrigerant entering the
evaporator and creates a pressure drop from the high side to the low side.
Proper metering is essential for maintaining appropriate evaporator
operation.
5. What happens to refrigerant pressure as it passes through a properly
operating expansion device?
A. It increases substantially
, B. It remains exactly constant
C. It decreases
D. It becomes atmospheric regardless of system design
Rationale: The expansion device separates the high-pressure and
lowpressure sides of the refrigeration circuit. Refrigerant experiences a
substantial pressure reduction as it enters the evaporator.
6. What is superheat?
A. The temperature of saturated liquid below its boiling point
B. The temperature of a vapor above its saturation temperature at a given
pressure
C. The pressure of liquid refrigerant below atmospheric pressure
D. The temperature difference between outdoor and indoor air only
Rationale: Superheat is the amount by which a vapor's actual temperature
exceeds its saturation temperature at the corresponding pressure. It is
commonly used to evaluate evaporator and refrigerant-system operation.
7. What is subcooling?
A. Heating refrigerant above its saturation temperature
Examination for HVAC Contractors
Exam Practice Questions And Correct
Answers (Verified Answers) Plus
Rationales 2027 Q&A | Instant
Download Pdf
1. Which component of a conventional vapor-compression HVAC system
absorbs heat from the conditioned space?
A. Condenser
B. Evaporator
C. Compressor
D. Receiver
,Rationale: The evaporator absorbs heat from the conditioned space as
refrigerant changes from a low-pressure liquid-vapor mixture toward
vapor. This heat absorption is the fundamental cooling process.
2. What is the primary function of the compressor in a vaporcompression
refrigeration system?
A. To remove moisture from indoor air
B. To reject heat directly to the conditioned space
C. To raise the pressure and temperature of refrigerant vapor and circulate
refrigerant through the system
D. To convert liquid refrigerant directly into ice
Rationale: The compressor draws in low-pressure refrigerant vapor from
the evaporator and compresses it into a higher-pressure,
highertemperature vapor that can reject heat in the condenser.
3. What is the primary function of the condenser in an air-conditioning
system?
A. To absorb heat from the conditioned space
B. To reject heat from the refrigerant to the surrounding environment
C. To lower indoor humidity exclusively
,D. To meter refrigerant into the evaporator
Rationale: The condenser removes heat from the high-pressure refrigerant
vapor and rejects that heat to outdoor air or another heat sink. The
refrigerant normally condenses into a liquid during this process.
4. What is the primary purpose of a metering device such as a
thermostatic expansion valve?
A. To increase refrigerant pressure before the compressor
B. To remove heat from the condenser
C. To regulate refrigerant flow into the evaporator and produce the
necessary pressure drop
D. To circulate condenser air
Rationale: The metering device controls refrigerant entering the
evaporator and creates a pressure drop from the high side to the low side.
Proper metering is essential for maintaining appropriate evaporator
operation.
5. What happens to refrigerant pressure as it passes through a properly
operating expansion device?
A. It increases substantially
, B. It remains exactly constant
C. It decreases
D. It becomes atmospheric regardless of system design
Rationale: The expansion device separates the high-pressure and
lowpressure sides of the refrigeration circuit. Refrigerant experiences a
substantial pressure reduction as it enters the evaporator.
6. What is superheat?
A. The temperature of saturated liquid below its boiling point
B. The temperature of a vapor above its saturation temperature at a given
pressure
C. The pressure of liquid refrigerant below atmospheric pressure
D. The temperature difference between outdoor and indoor air only
Rationale: Superheat is the amount by which a vapor's actual temperature
exceeds its saturation temperature at the corresponding pressure. It is
commonly used to evaluate evaporator and refrigerant-system operation.
7. What is subcooling?
A. Heating refrigerant above its saturation temperature
