NATE HEAT PUMP SERVICE EXAM NEWEST ACTUAL
EXAM COMPLETE 100 QUESTIONS AND CORRECT
DETAILED ANSWERS (VERIFIED ANSWERS) |ALREADY
GRADED A+||BRAND NEW VERSION!!
1. What is the primary purpose of the reversing valve in a heat pump system?
A. Control compressor speed
B. Reverse the flow of refrigerant (✓)
C. Regulate airflow
D. Increase subcooling
The reversing valve changes refrigerant direction to switch between heating and
cooling.
2. A heat pump operating in heating mode has low suction pressure and low
head pressure. What is the most likely cause?
A. Overcharge
B. Dirty indoor coil
C. Undercharge (✓)
D. Faulty compressor
Low suction + low head commonly indicates insufficient refrigerant.
3. What component prevents the outdoor coil from freezing during winter
operation?
A. Scroll compressor
B. TXV
C. Defrost control board (✓)
,D. Reversing valve
The defrost board monitors conditions and initiates defrost cycles.
4. During defrost, the heat pump temporarily operates in which mode?
A. Cooling mode (✓)
B. Heating mode
C. Dehumidification mode
D. Emergency mode
Defrost switches to cooling to melt frost on the outdoor coil.
5. What energizes the reversing valve in most heat pumps?
A. Heating mode
B. Cooling mode (✓)
C. Defrost mode
D. Emergency heat mode
Most manufacturers energize O in cooling.
6. A heat pump shows high superheat and low suction pressure. What is the
most probable cause?
A. Weak compressor
B. TXV restricted (✓)
C. Overcharge
D. Defrost board fault
Restriction starves the evaporator, increasing superheat.
7. What does the outdoor ambient temperature sensor control?
, A. Auxiliary heat lockout (✓)
B. Indoor blower speed
C. Indoor humidity
D. Compressor overload
It determines whether outdoor temperature is too low for efficient operation.
8. When does the auxiliary heat typically activate?
A. At night
B. During defrost cycles (✓)
C. During cooling
D. Above balance point
Aux heat warms the home while the system is in cooling mode for defrost.
9. What is the typical range of balance point for heat pumps?
A. 0–5°F
B. 10–15°F
C. 25–35°F (✓)
D. 45–55°F
Balance point depends on the home but is often around 30°F.
10. What is the function of a crankcase heater?
A. Increase discharge pressure
B. Prevent refrigerant migration into the compressor (✓)
C. Reduce superheat
D. Energize auxiliary heat
It keeps refrigerant out of the oil during the off cycle.
11. Low superheat and high suction pressure usually indicate what?
EXAM COMPLETE 100 QUESTIONS AND CORRECT
DETAILED ANSWERS (VERIFIED ANSWERS) |ALREADY
GRADED A+||BRAND NEW VERSION!!
1. What is the primary purpose of the reversing valve in a heat pump system?
A. Control compressor speed
B. Reverse the flow of refrigerant (✓)
C. Regulate airflow
D. Increase subcooling
The reversing valve changes refrigerant direction to switch between heating and
cooling.
2. A heat pump operating in heating mode has low suction pressure and low
head pressure. What is the most likely cause?
A. Overcharge
B. Dirty indoor coil
C. Undercharge (✓)
D. Faulty compressor
Low suction + low head commonly indicates insufficient refrigerant.
3. What component prevents the outdoor coil from freezing during winter
operation?
A. Scroll compressor
B. TXV
C. Defrost control board (✓)
,D. Reversing valve
The defrost board monitors conditions and initiates defrost cycles.
4. During defrost, the heat pump temporarily operates in which mode?
A. Cooling mode (✓)
B. Heating mode
C. Dehumidification mode
D. Emergency mode
Defrost switches to cooling to melt frost on the outdoor coil.
5. What energizes the reversing valve in most heat pumps?
A. Heating mode
B. Cooling mode (✓)
C. Defrost mode
D. Emergency heat mode
Most manufacturers energize O in cooling.
6. A heat pump shows high superheat and low suction pressure. What is the
most probable cause?
A. Weak compressor
B. TXV restricted (✓)
C. Overcharge
D. Defrost board fault
Restriction starves the evaporator, increasing superheat.
7. What does the outdoor ambient temperature sensor control?
, A. Auxiliary heat lockout (✓)
B. Indoor blower speed
C. Indoor humidity
D. Compressor overload
It determines whether outdoor temperature is too low for efficient operation.
8. When does the auxiliary heat typically activate?
A. At night
B. During defrost cycles (✓)
C. During cooling
D. Above balance point
Aux heat warms the home while the system is in cooling mode for defrost.
9. What is the typical range of balance point for heat pumps?
A. 0–5°F
B. 10–15°F
C. 25–35°F (✓)
D. 45–55°F
Balance point depends on the home but is often around 30°F.
10. What is the function of a crankcase heater?
A. Increase discharge pressure
B. Prevent refrigerant migration into the compressor (✓)
C. Reduce superheat
D. Energize auxiliary heat
It keeps refrigerant out of the oil during the off cycle.
11. Low superheat and high suction pressure usually indicate what?
