NATE Heat Pump Service Practice Exam
Newest Updated 150 Questions And
Correct Answers From Actual Past
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Rationales 2025|2026 Q&A | Instant
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1. What is the primary function of a reversing valve in a heat pump system?
A. Control refrigerant pressure
B. Change direction of refrigerant flow
C. Regulate airflow
D. Increase compressor speed
Answer: B. Change direction of refrigerant flow
The reversing valve allows the system to switch between heating and
cooling by reversing refrigerant flow.
2. In heating mode, where does a heat pump absorb heat from?
A. Indoor air
B. Refrigerant lines
C. Outdoor air
D. Compressor
Answer: C. Outdoor air
Even in cold temperatures, outdoor air contains heat energy that the
system extracts.
3. What component prevents liquid refrigerant from entering the compressor?
A. Condenser
B. Evaporator
, C. Accumulator
D. Expansion valve
Answer: C. Accumulator
The accumulator ensures only vapor refrigerant reaches the compressor.
4. What type of refrigerant metering device is commonly used in heat pumps?
A. Fixed orifice
B. TXV
C. Capillary tube
D. Float valve
Answer: B. TXV
Thermostatic expansion valves adjust flow based on load conditions.
5. What happens if a heat pump is low on refrigerant?
A. Increased efficiency
B. Reduced capacity
C. Higher airflow
D. Faster heating
Answer: B. Reduced capacity
Low refrigerant reduces heat transfer capability.
6. What is the purpose of defrost mode?
A. Increase airflow
B. Melt ice on outdoor coil
C. Improve cooling
D. Reduce pressure
Answer: B. Melt ice on outdoor coil
Defrost cycles remove frost buildup that blocks airflow.
7. Which sensor initiates defrost cycle?
A. Pressure switch
B. Thermostat
C. Defrost thermostat
D. Relay
, Answer: C. Defrost thermostat
It detects coil temperature and signals defrost when needed.
8. What is auxiliary heat?
A. Backup heating source
B. Cooling enhancement
C. Compressor support
D. Airflow control
Answer: A. Backup heating source
Aux heat supplements heating when the heat pump cannot meet demand.
9. What is a common auxiliary heat source?
A. Gas burner
B. Electric resistance heaters
C. Solar panels
D. Water coil
Answer: B. Electric resistance heaters
Electric heat strips are commonly used as backup heat.
10.What does COP stand for?
A. Coefficient of Performance
B. Cooling Output Power
C. Compressor Operation Pressure
D. Coil Operating Point
Answer: A. Coefficient of Performance
COP measures efficiency by comparing output heat to input energy.
11.A high COP indicates what?
A. Low efficiency
B. High efficiency
C. High pressure
D. Low airflow
Answer: B. High efficiency
Higher COP means more heat output per unit of energy input.
, 12.What component compresses refrigerant vapor?
A. Evaporator
B. Compressor
C. Condenser
D. Metering device
Answer: B. Compressor
The compressor increases pressure and temperature of refrigerant.
13.What is superheat?
A. Liquid above boiling point
B. Vapor above saturation temperature
C. Pressure increase
D. Air temperature
Answer: B. Vapor above saturation temperature
Superheat ensures no liquid remains in refrigerant vapor.
14.What is subcooling?
A. Vapor cooling
B. Liquid below saturation temperature
C. Pressure drop
D. Airflow reduction
Answer: B. Liquid below saturation temperature
Subcooling confirms refrigerant is fully condensed.
15.What is the main purpose of the outdoor coil in heating mode?
A. Condense refrigerant
B. Absorb heat
C. Increase airflow
D. Reduce pressure
Answer: B. Absorb heat
In heating mode, the outdoor coil acts as the evaporator.
16.What is the indoor coil function in heating mode?
A. Evaporate refrigerant
B. Condense refrigerant
Newest Updated 150 Questions And
Correct Answers From Actual Past
Papers Exams (Graded A+) Plus
Rationales 2025|2026 Q&A | Instant
Download Pdf
1. What is the primary function of a reversing valve in a heat pump system?
A. Control refrigerant pressure
B. Change direction of refrigerant flow
C. Regulate airflow
D. Increase compressor speed
Answer: B. Change direction of refrigerant flow
The reversing valve allows the system to switch between heating and
cooling by reversing refrigerant flow.
2. In heating mode, where does a heat pump absorb heat from?
A. Indoor air
B. Refrigerant lines
C. Outdoor air
D. Compressor
Answer: C. Outdoor air
Even in cold temperatures, outdoor air contains heat energy that the
system extracts.
3. What component prevents liquid refrigerant from entering the compressor?
A. Condenser
B. Evaporator
, C. Accumulator
D. Expansion valve
Answer: C. Accumulator
The accumulator ensures only vapor refrigerant reaches the compressor.
4. What type of refrigerant metering device is commonly used in heat pumps?
A. Fixed orifice
B. TXV
C. Capillary tube
D. Float valve
Answer: B. TXV
Thermostatic expansion valves adjust flow based on load conditions.
5. What happens if a heat pump is low on refrigerant?
A. Increased efficiency
B. Reduced capacity
C. Higher airflow
D. Faster heating
Answer: B. Reduced capacity
Low refrigerant reduces heat transfer capability.
6. What is the purpose of defrost mode?
A. Increase airflow
B. Melt ice on outdoor coil
C. Improve cooling
D. Reduce pressure
Answer: B. Melt ice on outdoor coil
Defrost cycles remove frost buildup that blocks airflow.
7. Which sensor initiates defrost cycle?
A. Pressure switch
B. Thermostat
C. Defrost thermostat
D. Relay
, Answer: C. Defrost thermostat
It detects coil temperature and signals defrost when needed.
8. What is auxiliary heat?
A. Backup heating source
B. Cooling enhancement
C. Compressor support
D. Airflow control
Answer: A. Backup heating source
Aux heat supplements heating when the heat pump cannot meet demand.
9. What is a common auxiliary heat source?
A. Gas burner
B. Electric resistance heaters
C. Solar panels
D. Water coil
Answer: B. Electric resistance heaters
Electric heat strips are commonly used as backup heat.
10.What does COP stand for?
A. Coefficient of Performance
B. Cooling Output Power
C. Compressor Operation Pressure
D. Coil Operating Point
Answer: A. Coefficient of Performance
COP measures efficiency by comparing output heat to input energy.
11.A high COP indicates what?
A. Low efficiency
B. High efficiency
C. High pressure
D. Low airflow
Answer: B. High efficiency
Higher COP means more heat output per unit of energy input.
, 12.What component compresses refrigerant vapor?
A. Evaporator
B. Compressor
C. Condenser
D. Metering device
Answer: B. Compressor
The compressor increases pressure and temperature of refrigerant.
13.What is superheat?
A. Liquid above boiling point
B. Vapor above saturation temperature
C. Pressure increase
D. Air temperature
Answer: B. Vapor above saturation temperature
Superheat ensures no liquid remains in refrigerant vapor.
14.What is subcooling?
A. Vapor cooling
B. Liquid below saturation temperature
C. Pressure drop
D. Airflow reduction
Answer: B. Liquid below saturation temperature
Subcooling confirms refrigerant is fully condensed.
15.What is the main purpose of the outdoor coil in heating mode?
A. Condense refrigerant
B. Absorb heat
C. Increase airflow
D. Reduce pressure
Answer: B. Absorb heat
In heating mode, the outdoor coil acts as the evaporator.
16.What is the indoor coil function in heating mode?
A. Evaporate refrigerant
B. Condense refrigerant
