1|Page
NATE AC Service Certification Exam Latest 2025
Actual Exam| Complete 100 Real Exam Questions and
Correct Verified Answers/ Graded A+ (New!!)
Which measures duct static pressure?
A. Anemometer
B. Air balance hood
C. Mechanical velometer
D. Differential pressure gauge - Correct Answer - 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. - Correct Answer - 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
pg. 1
,2|Page
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. - Correct Answer - 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 - Correct Answer - 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. - Correct Answer - C
pg. 2
,3|Page
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. - Correct Answer - A
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. - Correct Answer - A. humidity
problems.
Electronic air cleaners can operate with internal voltages as high as:
A. 120 volts.
B. 240 volts.
C. 500 volts.
D. 5000 volts. - Correct Answer - D. 5000 volts.
The lubricating oil primarily used with R-22 air conditioning
compressors is:
A. Polyolesters (POE).
B. Mineral oil based.
pg. 3
, 4|Page
C. Alkybenzenes.
D. Polyalkylene Glycol (PAG). - Correct Answer - B. Mineral oil based.
When an air conditioner with a thermostatic expansion valve installed is
overcharged, the excess charge should be removed by recovering some
charge and checking:
A. system pressures.
B. superheat.
C. subcooling.
D. head pressure. - Correct Answer - C. subcooling
With an R-410A condensing pressure of 397 psig and a liquid line
temperature of 108degF, what is the subcooling temperature?
A. 36degF
B. 24degF
C. 16degF
D. 8degF - Correct Answer - D. 8degF
What is the maximum acceptable supply voltage tolerance for a 120 V
circuit?
A. +/-3%
B. +/-5%
C. +/-10%
D. +10% / -15% - Correct Answer - B. +/-5%
pg. 4
NATE AC Service Certification Exam Latest 2025
Actual Exam| Complete 100 Real Exam Questions and
Correct Verified Answers/ Graded A+ (New!!)
Which measures duct static pressure?
A. Anemometer
B. Air balance hood
C. Mechanical velometer
D. Differential pressure gauge - Correct Answer - 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. - Correct Answer - 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
pg. 1
,2|Page
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. - Correct Answer - 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 - Correct Answer - 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. - Correct Answer - C
pg. 2
,3|Page
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. - Correct Answer - A
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. - Correct Answer - A. humidity
problems.
Electronic air cleaners can operate with internal voltages as high as:
A. 120 volts.
B. 240 volts.
C. 500 volts.
D. 5000 volts. - Correct Answer - D. 5000 volts.
The lubricating oil primarily used with R-22 air conditioning
compressors is:
A. Polyolesters (POE).
B. Mineral oil based.
pg. 3
, 4|Page
C. Alkybenzenes.
D. Polyalkylene Glycol (PAG). - Correct Answer - B. Mineral oil based.
When an air conditioner with a thermostatic expansion valve installed is
overcharged, the excess charge should be removed by recovering some
charge and checking:
A. system pressures.
B. superheat.
C. subcooling.
D. head pressure. - Correct Answer - C. subcooling
With an R-410A condensing pressure of 397 psig and a liquid line
temperature of 108degF, what is the subcooling temperature?
A. 36degF
B. 24degF
C. 16degF
D. 8degF - Correct Answer - D. 8degF
What is the maximum acceptable supply voltage tolerance for a 120 V
circuit?
A. +/-3%
B. +/-5%
C. +/-10%
D. +10% / -15% - Correct Answer - B. +/-5%
pg. 4
