NATE AIR CONDITIONING AND HEAT PUMP TEST PAPER
2025/2026 QUESTIONS WITH ANSWERS GRADED A+
✔✔A technician has the following conditions while checking a packaged heat pump in
cooling...
- the unit has a piston type metering device on both the indoor and outdoor coils
- outdoor temperature 75(F)
- superheat 55(F)
The diagnosis and corrective action is... - ✔✔that the unit is low on charge and a charge
needs to be added
✔✔The effect of adding a charge to sub-cooling is... - ✔✔it increases it
✔✔When a capillary tube is overcharged... - ✔✔you would get a low superheat and
high sub-cooling
✔✔The effect of a low charge on the switch=over operations of a reversing valve is... -
✔✔the reversing valves are less likely to transfer if charge is low
✔✔A technician is working on a heat pump with a capacitor start-capacitor run
compressor. On initial startup, the compressor hums momentarily and then shuts down
on internal overload, the problem is... - ✔✔too great a pressure difference on
compressor
✔✔A step down transformer has a rating of 40 volt-amps. Its primary voltage is 120v
with a secondary voltage of 24v. This transformer must not be... - ✔✔connected to a
load above a maximum current draw of 1.7 amps
✔✔A bright red or orange glow from the resistance element in a duct heater indicates
that... - ✔✔the flow of air is insufficient
✔✔The outdoor fan on a heat pump stops during defrost to... - ✔✔minimize defrost time
✔✔A capacitorr start-capacitor run (CSCR) motor has an open run capacitor so it may
start, but it... - ✔✔draws a higher than normal running current
✔✔Bent vanes on a direct drive blower wheel in an air handler can cause... - ✔✔loss in
airflow, excessive motor wear, and increased noise
✔✔A split system heat pump is using thermostatic expansion valves. The system
performs properly in heating but in cooling the compressor pumps down, which could
mean... - ✔✔the power element of the indoor expansion valve has lost its charge
, ✔✔Conditions that can cause a reduction from design capacity in a heat pump are... -
✔✔an undersized vapor line
✔✔Flash gas in the liquid line of any heat pump must be avoided. Liquid line flash gas
can be caused by... - ✔✔excessive liquid line length or lift
✔✔A symptom that a technician would expect on a heat pump system in the cooling
mode if the check valve is leaking internally is... - ✔✔a flooding of the indoor coil
✔✔A voltage reading across a closed contact in a 24v control circuit indicates... -
✔✔pitted or dirty contacts
✔✔The first two checks typically made on an electronic control are... - ✔✔presence of
proper input signals and proper output voltages
✔✔In a low voltage circuit, a corroded wire-to-terminal connection acts in the circuit
like... - ✔✔an additional resistor
✔✔The continuity of a fuse should be tested by... - ✔✔checking resistance with power
off
✔✔The first check made for most electrical troubleshooting is a... - ✔✔voltage check of
the supply line
✔✔To properly check an energized compressor circuit, the technician should... - ✔✔use
a VOM set for volts
✔✔The following conditions exist in a circuit that supplies power to three parallel loads...
One load is resistive
One load is capactive
One load is inductive
The current in the circuit when operating will be... - ✔✔the sum of the currents through
each load
✔✔The technician is using an analog multimeter to check a run capacitor. With the
meter set to ohms the needle swings toward zero and then slowly rises toward infinity.
This tells the technician... - ✔✔that the capacitor charges and discharges
✔✔If the technician believes that a hermetic compressor has a permanently open
internal overload protector, the technician should... - ✔✔test the compresssor while it is
cool
2025/2026 QUESTIONS WITH ANSWERS GRADED A+
✔✔A technician has the following conditions while checking a packaged heat pump in
cooling...
- the unit has a piston type metering device on both the indoor and outdoor coils
- outdoor temperature 75(F)
- superheat 55(F)
The diagnosis and corrective action is... - ✔✔that the unit is low on charge and a charge
needs to be added
✔✔The effect of adding a charge to sub-cooling is... - ✔✔it increases it
✔✔When a capillary tube is overcharged... - ✔✔you would get a low superheat and
high sub-cooling
✔✔The effect of a low charge on the switch=over operations of a reversing valve is... -
✔✔the reversing valves are less likely to transfer if charge is low
✔✔A technician is working on a heat pump with a capacitor start-capacitor run
compressor. On initial startup, the compressor hums momentarily and then shuts down
on internal overload, the problem is... - ✔✔too great a pressure difference on
compressor
✔✔A step down transformer has a rating of 40 volt-amps. Its primary voltage is 120v
with a secondary voltage of 24v. This transformer must not be... - ✔✔connected to a
load above a maximum current draw of 1.7 amps
✔✔A bright red or orange glow from the resistance element in a duct heater indicates
that... - ✔✔the flow of air is insufficient
✔✔The outdoor fan on a heat pump stops during defrost to... - ✔✔minimize defrost time
✔✔A capacitorr start-capacitor run (CSCR) motor has an open run capacitor so it may
start, but it... - ✔✔draws a higher than normal running current
✔✔Bent vanes on a direct drive blower wheel in an air handler can cause... - ✔✔loss in
airflow, excessive motor wear, and increased noise
✔✔A split system heat pump is using thermostatic expansion valves. The system
performs properly in heating but in cooling the compressor pumps down, which could
mean... - ✔✔the power element of the indoor expansion valve has lost its charge
, ✔✔Conditions that can cause a reduction from design capacity in a heat pump are... -
✔✔an undersized vapor line
✔✔Flash gas in the liquid line of any heat pump must be avoided. Liquid line flash gas
can be caused by... - ✔✔excessive liquid line length or lift
✔✔A symptom that a technician would expect on a heat pump system in the cooling
mode if the check valve is leaking internally is... - ✔✔a flooding of the indoor coil
✔✔A voltage reading across a closed contact in a 24v control circuit indicates... -
✔✔pitted or dirty contacts
✔✔The first two checks typically made on an electronic control are... - ✔✔presence of
proper input signals and proper output voltages
✔✔In a low voltage circuit, a corroded wire-to-terminal connection acts in the circuit
like... - ✔✔an additional resistor
✔✔The continuity of a fuse should be tested by... - ✔✔checking resistance with power
off
✔✔The first check made for most electrical troubleshooting is a... - ✔✔voltage check of
the supply line
✔✔To properly check an energized compressor circuit, the technician should... - ✔✔use
a VOM set for volts
✔✔The following conditions exist in a circuit that supplies power to three parallel loads...
One load is resistive
One load is capactive
One load is inductive
The current in the circuit when operating will be... - ✔✔the sum of the currents through
each load
✔✔The technician is using an analog multimeter to check a run capacitor. With the
meter set to ohms the needle swings toward zero and then slowly rises toward infinity.
This tells the technician... - ✔✔that the capacitor charges and discharges
✔✔If the technician believes that a hermetic compressor has a permanently open
internal overload protector, the technician should... - ✔✔test the compresssor while it is
cool
