NATE AC SERVICE CERTIFICATION 2026 ALL EXAM
QUESTIONS AND ANSWERS SURE A+
✔✔Electronic type leak detectors typically have a push-button or knob for setting a
reference refrigerant level. This feature is useful for:
A. adjusting the detector after installing a new battery.
B. checking the factory calibration of the instrument.
C. setting the detector for use in environments with ambient refrigerant vapor.
D. adjusting the detector for the type refrigerant to be checked. - ✔✔C. setting the
detector for use in environments with ambient refrigerant vapor.
✔✔What will refrigerant oil in a hose cause when a technician is checking the pressures
in an operation system with a manifold gauge set?
A. All readings on that gauge will increase in value.
B. All readings on that gauge will decrease in value.
C. All readings on that gauge will not be affected.
D. The gauge will read 0 psig. - ✔✔C. All readings on that gauge will not be affected.
✔✔Which measures duct static pressure?
A. Anemometer
,B. Air balance hood
C. Mechanical velometer
D. Differential pressure gauge - ✔✔C. Mechanical velometer
✔✔A duct 36 in. x 24 in. that has an average velocity of 600 fpm is handling:
A. 3600 CFM.
B. 2400 CFM.
C. 1200 CFM.
D. 1000 CFM. - ✔✔A. 3600 CFM.
CFM = Velocity x Area (ft.^2)
CFM = 600fpm x ((36 x 24)/144)) (convert to sq. ft.)
CFM = 600fpm x 6sqft
CFM = 3600 CFM
✔✔What steps are necessary to clean a two row curved condenser coil?
A. Spray the coil from the inside of the condenser with a soap base coil cleaner
B. Spray the coil from the inside and the outside of the condenser with an acid base
cleaner
C. Brush the outside of the condenser with a bristle brush and water flush
D. Separate the two rows of coils, spray all surfaces with proper coil cleaner and water
flush - ✔✔*D. Separate the two rows of coils, spray all surfaces with proper coil cleaner
and water flush
✔✔A residential supply diffuser that is noisy because of a loose vane is best serviced
by:
A. reducing the air volume.
B. changing the fan speed.
C. replacing the noisy vane.
D. replacing the diffuser. - ✔✔D. replacing the diffuser.
✔✔Which of the following is a likely problem if the air across the evaporator of an air
conditioner has a high temperature differential?
A. Too much charge
B. Clogged expansion valve
C. Dirty filter or evaporator
D. Dirty condenser coil - ✔✔*C
✔✔When performing a cycling check during a maintenance call, the technician should
first check with the owner of the equipment for their opinion of performance. The next
, step is to turn the unit off at the thermostat SYSTEM switch. The technician should set
the FAN switch to:
A. AUTO and measure the voltage from the R to G terminal.
B. ON and measure the voltage from the R to the W1 terminal.
C. ON and check that the blower is running.
D. AUTO and check that the blower is running. - ✔✔*C
✔✔To properly check the computer and its line voltage wiring the technician should
measure resistance at the:
A. load side of the compressor contactor.
B. compressor terminals.
C. capacitor.
D. crankcase heater. - ✔✔*A
✔✔On a residential no cooling call, typically the first check would be:
A. the air filter.
B. the control voltage at the transformer.
C. if the thermostat is calling for cooling.
D. the refrigerant system pressures. - ✔✔C. if the thermostat is calling for cooling.
✔✔What could cause a customer to complain that their home feels damp or "sticky"?
A. Low evaporator airflow
B. Returns may be pulling in unconditioned air
C. The system is undersized
D. Air filter is clogged or dirty - ✔✔B. Returns may be pulling in unconditioned air
✔✔A system supply airflow check is used to diagnose:
A. humidity problems.
B. compressor overheating.
C. restricted liquid line drier
D. condenser fan motor overheating. - ✔✔A. humidity problems.
✔✔A technician finds a R-410A system with the following:
*Suction pressure is 105 psi
*Suction line temperature is 75degF
*Recommended superheat is 20degF
This indicates the system:
A. is overcharged.
B. has excess airflow
QUESTIONS AND ANSWERS SURE A+
✔✔Electronic type leak detectors typically have a push-button or knob for setting a
reference refrigerant level. This feature is useful for:
A. adjusting the detector after installing a new battery.
B. checking the factory calibration of the instrument.
C. setting the detector for use in environments with ambient refrigerant vapor.
D. adjusting the detector for the type refrigerant to be checked. - ✔✔C. setting the
detector for use in environments with ambient refrigerant vapor.
✔✔What will refrigerant oil in a hose cause when a technician is checking the pressures
in an operation system with a manifold gauge set?
A. All readings on that gauge will increase in value.
B. All readings on that gauge will decrease in value.
C. All readings on that gauge will not be affected.
D. The gauge will read 0 psig. - ✔✔C. All readings on that gauge will not be affected.
✔✔Which measures duct static pressure?
A. Anemometer
,B. Air balance hood
C. Mechanical velometer
D. Differential pressure gauge - ✔✔C. Mechanical velometer
✔✔A duct 36 in. x 24 in. that has an average velocity of 600 fpm is handling:
A. 3600 CFM.
B. 2400 CFM.
C. 1200 CFM.
D. 1000 CFM. - ✔✔A. 3600 CFM.
CFM = Velocity x Area (ft.^2)
CFM = 600fpm x ((36 x 24)/144)) (convert to sq. ft.)
CFM = 600fpm x 6sqft
CFM = 3600 CFM
✔✔What steps are necessary to clean a two row curved condenser coil?
A. Spray the coil from the inside of the condenser with a soap base coil cleaner
B. Spray the coil from the inside and the outside of the condenser with an acid base
cleaner
C. Brush the outside of the condenser with a bristle brush and water flush
D. Separate the two rows of coils, spray all surfaces with proper coil cleaner and water
flush - ✔✔*D. Separate the two rows of coils, spray all surfaces with proper coil cleaner
and water flush
✔✔A residential supply diffuser that is noisy because of a loose vane is best serviced
by:
A. reducing the air volume.
B. changing the fan speed.
C. replacing the noisy vane.
D. replacing the diffuser. - ✔✔D. replacing the diffuser.
✔✔Which of the following is a likely problem if the air across the evaporator of an air
conditioner has a high temperature differential?
A. Too much charge
B. Clogged expansion valve
C. Dirty filter or evaporator
D. Dirty condenser coil - ✔✔*C
✔✔When performing a cycling check during a maintenance call, the technician should
first check with the owner of the equipment for their opinion of performance. The next
, step is to turn the unit off at the thermostat SYSTEM switch. The technician should set
the FAN switch to:
A. AUTO and measure the voltage from the R to G terminal.
B. ON and measure the voltage from the R to the W1 terminal.
C. ON and check that the blower is running.
D. AUTO and check that the blower is running. - ✔✔*C
✔✔To properly check the computer and its line voltage wiring the technician should
measure resistance at the:
A. load side of the compressor contactor.
B. compressor terminals.
C. capacitor.
D. crankcase heater. - ✔✔*A
✔✔On a residential no cooling call, typically the first check would be:
A. the air filter.
B. the control voltage at the transformer.
C. if the thermostat is calling for cooling.
D. the refrigerant system pressures. - ✔✔C. if the thermostat is calling for cooling.
✔✔What could cause a customer to complain that their home feels damp or "sticky"?
A. Low evaporator airflow
B. Returns may be pulling in unconditioned air
C. The system is undersized
D. Air filter is clogged or dirty - ✔✔B. Returns may be pulling in unconditioned air
✔✔A system supply airflow check is used to diagnose:
A. humidity problems.
B. compressor overheating.
C. restricted liquid line drier
D. condenser fan motor overheating. - ✔✔A. humidity problems.
✔✔A technician finds a R-410A system with the following:
*Suction pressure is 105 psi
*Suction line temperature is 75degF
*Recommended superheat is 20degF
This indicates the system:
A. is overcharged.
B. has excess airflow
