NATE Heat Pump Exam ACTUAL
EXAM 2026/2027: 100% Verified
Questions & Correct Answers
Question 1: A technician is troubleshooting a heat pump system in heating mode. The outdoor
ambient temperature is 35°F, and the system is experiencing low suction pressure. The refrigerant
line temperature at the outdoor coil outlet is 28°F. What is the most likely cause?
A. Overcharged system
B. Restricted outdoor coil airflow
C. Failed reversing valve
D. Defective compressor
Correct Answer: B
Rationale: Low suction pressure with a refrigerant line temperature below freezing indicates
insufficient heat transfer at the outdoor coil, typically caused by restricted airflow from dirty coils,
blocked fan, or debris accumulation.
Question 2: During heat pump installation, the technician measures 240V between L1 and L2 at
the outdoor unit contactor, but 0V between L1 and ground. What should be the immediate action?
A. Replace the contactor
B. Check the main electrical panel for a tripped breaker or loose neutral
C. Replace the transformer
,D. Check the thermostat wiring
Correct Answer: B
Rationale: Zero voltage between L1 and ground indicates a missing neutral connection or tripped
breaker, which is a safety hazard that must be addressed before proceeding with system operation.
Question 3: A heat pump system has a measured superheat of 3°F in cooling mode with proper
airflow. The manufacturer specifies 10-12°F superheat. What is the most appropriate adjustment?
A. Add refrigerant
B. Remove refrigerant
C. Replace the expansion valve
D. Increase blower speed
Correct Answer: B
Rationale: Low superheat indicates overcharge condition. Removing refrigerant will increase
superheat to the manufacturer's specified range, ensuring proper system operation and
compressor protection.
Question 4: During defrost cycle initiation, the technician observes that the outdoor fan continues
to run. What component failure would cause this condition?
A. Defrost thermostat
B. Defrost relay contacts welded closed
C. Reversing valve solenoid
D. Outdoor fan motor capacitor
Correct Answer: B
,Rationale: The defrost relay should de-energize the outdoor fan during defrost. Welded contacts
prevent the relay from opening, causing the fan to continue running when it should be off.
Question 5: A heat pump operating in heating mode has a discharge air temperature of 85°F with
70°F return air. The outdoor temperature is 40°F. What does this indicate?
A. Normal operation
B. Supplemental electric heat is energized
C. Reversing valve stuck in cooling position
D. Low refrigerant charge
Correct Answer: B
Rationale: A 15°F temperature rise is excessive for a heat pump alone at 40°F outdoor
temperature, indicating that supplemental electric heat is operating, either due to thermostat
setting or control logic.
Question 6: The technician measures 24VAC at the reversing valve solenoid but the valve does not
shift. What is the most likely cause?
A. Low refrigerant charge
B. Defective reversing valve solenoid coil
C. Failed defrost control board
D. Restricted liquid line drier
Correct Answer: B
Rationale: Proper voltage at the solenoid with no valve movement indicates the solenoid coil is
defective. The coil creates the electromagnetic field needed to shift the valve's internal slide
mechanism.
, Question 7: During heat pump startup in cooling mode, the technician notices the suction pressure
immediately drops to 30 psig and remains there. The outdoor temperature is 85°F. What is the
likely problem?
A. Overcharged system
B. Restricted metering device
C. Oversized system
D. Defective compressor valves
Correct Answer: B
Rationale: An immediate and sustained low suction pressure indicates a restriction in the
refrigerant flow, most commonly at the metering device, preventing proper refrigerant circulation.
Question 8: A homeowner reports insufficient heating. The technician finds the heat pump running
continuously with outdoor coil heavily frosted. The defrost thermostat contacts are closed. What
should be checked first?
A. Reversing valve operation
B. Defrost control board timing and operation
C. Refrigerant charge level
D. Outdoor fan motor amperage
Correct Answer: B
Rationale: Heavy frost accumulation with closed defrost thermostat contacts suggests the defrost
control board is not initiating defrost cycles, indicating a control board malfunction or incorrect
timing settings.
EXAM 2026/2027: 100% Verified
Questions & Correct Answers
Question 1: A technician is troubleshooting a heat pump system in heating mode. The outdoor
ambient temperature is 35°F, and the system is experiencing low suction pressure. The refrigerant
line temperature at the outdoor coil outlet is 28°F. What is the most likely cause?
A. Overcharged system
B. Restricted outdoor coil airflow
C. Failed reversing valve
D. Defective compressor
Correct Answer: B
Rationale: Low suction pressure with a refrigerant line temperature below freezing indicates
insufficient heat transfer at the outdoor coil, typically caused by restricted airflow from dirty coils,
blocked fan, or debris accumulation.
Question 2: During heat pump installation, the technician measures 240V between L1 and L2 at
the outdoor unit contactor, but 0V between L1 and ground. What should be the immediate action?
A. Replace the contactor
B. Check the main electrical panel for a tripped breaker or loose neutral
C. Replace the transformer
,D. Check the thermostat wiring
Correct Answer: B
Rationale: Zero voltage between L1 and ground indicates a missing neutral connection or tripped
breaker, which is a safety hazard that must be addressed before proceeding with system operation.
Question 3: A heat pump system has a measured superheat of 3°F in cooling mode with proper
airflow. The manufacturer specifies 10-12°F superheat. What is the most appropriate adjustment?
A. Add refrigerant
B. Remove refrigerant
C. Replace the expansion valve
D. Increase blower speed
Correct Answer: B
Rationale: Low superheat indicates overcharge condition. Removing refrigerant will increase
superheat to the manufacturer's specified range, ensuring proper system operation and
compressor protection.
Question 4: During defrost cycle initiation, the technician observes that the outdoor fan continues
to run. What component failure would cause this condition?
A. Defrost thermostat
B. Defrost relay contacts welded closed
C. Reversing valve solenoid
D. Outdoor fan motor capacitor
Correct Answer: B
,Rationale: The defrost relay should de-energize the outdoor fan during defrost. Welded contacts
prevent the relay from opening, causing the fan to continue running when it should be off.
Question 5: A heat pump operating in heating mode has a discharge air temperature of 85°F with
70°F return air. The outdoor temperature is 40°F. What does this indicate?
A. Normal operation
B. Supplemental electric heat is energized
C. Reversing valve stuck in cooling position
D. Low refrigerant charge
Correct Answer: B
Rationale: A 15°F temperature rise is excessive for a heat pump alone at 40°F outdoor
temperature, indicating that supplemental electric heat is operating, either due to thermostat
setting or control logic.
Question 6: The technician measures 24VAC at the reversing valve solenoid but the valve does not
shift. What is the most likely cause?
A. Low refrigerant charge
B. Defective reversing valve solenoid coil
C. Failed defrost control board
D. Restricted liquid line drier
Correct Answer: B
Rationale: Proper voltage at the solenoid with no valve movement indicates the solenoid coil is
defective. The coil creates the electromagnetic field needed to shift the valve's internal slide
mechanism.
, Question 7: During heat pump startup in cooling mode, the technician notices the suction pressure
immediately drops to 30 psig and remains there. The outdoor temperature is 85°F. What is the
likely problem?
A. Overcharged system
B. Restricted metering device
C. Oversized system
D. Defective compressor valves
Correct Answer: B
Rationale: An immediate and sustained low suction pressure indicates a restriction in the
refrigerant flow, most commonly at the metering device, preventing proper refrigerant circulation.
Question 8: A homeowner reports insufficient heating. The technician finds the heat pump running
continuously with outdoor coil heavily frosted. The defrost thermostat contacts are closed. What
should be checked first?
A. Reversing valve operation
B. Defrost control board timing and operation
C. Refrigerant charge level
D. Outdoor fan motor amperage
Correct Answer: B
Rationale: Heavy frost accumulation with closed defrost thermostat contacts suggests the defrost
control board is not initiating defrost cycles, indicating a control board malfunction or incorrect
timing settings.
