NATE AC Service Certification
A system is supplied from the factory with charge of 5 pounds 10 ounces for a 15 foot line set. The line
set is 25 feet long. The manufacturer's instruction sheet specifies 0.6 ounces of refrigeration to be added
for each added foot of refrigerant line set length. What is the total refrigerant charge for the system?
A. 6 ounces
B. 5 pounds
C. 5 pounds 10 ounces
D. 6 pounds - ✔✔ correct answer D. 6 pounds
15ft - 25ft = 10ft x .6 = 6 ounces
5 pounds + 10 ounces + 6 ounces
5 pounds + 16 ounces = 6 pounds
The purpose of using flux when soldering is to:
A. anneal the surface.
B. give better heat flow.
C. reduce oxidation.
D. pre-seal the oxidation. - ✔✔ correct answer C. reduce oxidation.
Outdoor condensing units that are installed in areas where flooding is possible must:
A. be mounted above flood level.
B. utilize NEMA 1 enclosures.
C. be mounted under an overhanging eave.
D. use water resistant components. - ✔✔ correct answer A. be mounted above flood level.
The component used to reduce sound transmission and prevent water leaks on a rooftop air conditioner
packaged unit installation is the:
,NATE AC Service Certification
A. curb gasket.
B. silicone caulk.
C. roof flashing.
D. roofing tar. - ✔✔ correct answer A. curb gasket.
Return air leakage in a hot attic will:
A. Increase capacity
B. Decrease capacity
C. Increase airflow
D. Decrease airflow - ✔✔ correct answer B. Decrease capacity
An air conditioner refrigerant circuit should be evacuated to a minimum of:
A. 0 microns.
B. 200 microns.
C. 500 microns.
D. 1200 microns. - ✔✔ correct answer C. 500 microns.
Which of the following substances could create an extremely dangerous condition if used to check
refrigeration system for leaks?
A. R-22
B. Nitrogen
C. Oxygen
D. Carbon Dioxide - ✔✔ correct answer D. Carbon Dioxide
The subcooling method for checking charge is generally used on air conditioners with what type of
metering?
, NATE AC Service Certification
A. Only externally equalized thermostatic expansion valves
B. Any thermostatic expansion valve
C. Piston type
D. Any fixed metering device - ✔✔ correct answer B. Any thermostatic expansion valve
Supply ducts running through unconditioned space should be insulated and have:
A. equal friction.
B. excessive air velocity.
C. a vapor barrier.
D. a transition backing. - ✔✔ correct answer C. a vapor barrier.
An important consideration when installing a motorized economizer is to check to be certain that:
A. the vanes are set for a maximum 10% outdoor air.
B. the vanes open on any call for cooling.
C. the vanes operate without binding.
D. the vanes are permanently set at 50%. - ✔✔ correct answer C. the vanes operate without binding.
On a 3 ton unit installation, the measure airflow equals 1550 CFM. What does this indicate?
A. Proper balancing
B. Low Airflow
C. Excess airflow
D. Improper balancing - ✔✔ correct answer C. Excess airflow(400cfm per ton, 3 ton=1200cfm)
Electronic type leak detectors typically have a push-button or knob for setting a reference refrigerant
level. This feature is useful for:
A system is supplied from the factory with charge of 5 pounds 10 ounces for a 15 foot line set. The line
set is 25 feet long. The manufacturer's instruction sheet specifies 0.6 ounces of refrigeration to be added
for each added foot of refrigerant line set length. What is the total refrigerant charge for the system?
A. 6 ounces
B. 5 pounds
C. 5 pounds 10 ounces
D. 6 pounds - ✔✔ correct answer D. 6 pounds
15ft - 25ft = 10ft x .6 = 6 ounces
5 pounds + 10 ounces + 6 ounces
5 pounds + 16 ounces = 6 pounds
The purpose of using flux when soldering is to:
A. anneal the surface.
B. give better heat flow.
C. reduce oxidation.
D. pre-seal the oxidation. - ✔✔ correct answer C. reduce oxidation.
Outdoor condensing units that are installed in areas where flooding is possible must:
A. be mounted above flood level.
B. utilize NEMA 1 enclosures.
C. be mounted under an overhanging eave.
D. use water resistant components. - ✔✔ correct answer A. be mounted above flood level.
The component used to reduce sound transmission and prevent water leaks on a rooftop air conditioner
packaged unit installation is the:
,NATE AC Service Certification
A. curb gasket.
B. silicone caulk.
C. roof flashing.
D. roofing tar. - ✔✔ correct answer A. curb gasket.
Return air leakage in a hot attic will:
A. Increase capacity
B. Decrease capacity
C. Increase airflow
D. Decrease airflow - ✔✔ correct answer B. Decrease capacity
An air conditioner refrigerant circuit should be evacuated to a minimum of:
A. 0 microns.
B. 200 microns.
C. 500 microns.
D. 1200 microns. - ✔✔ correct answer C. 500 microns.
Which of the following substances could create an extremely dangerous condition if used to check
refrigeration system for leaks?
A. R-22
B. Nitrogen
C. Oxygen
D. Carbon Dioxide - ✔✔ correct answer D. Carbon Dioxide
The subcooling method for checking charge is generally used on air conditioners with what type of
metering?
, NATE AC Service Certification
A. Only externally equalized thermostatic expansion valves
B. Any thermostatic expansion valve
C. Piston type
D. Any fixed metering device - ✔✔ correct answer B. Any thermostatic expansion valve
Supply ducts running through unconditioned space should be insulated and have:
A. equal friction.
B. excessive air velocity.
C. a vapor barrier.
D. a transition backing. - ✔✔ correct answer C. a vapor barrier.
An important consideration when installing a motorized economizer is to check to be certain that:
A. the vanes are set for a maximum 10% outdoor air.
B. the vanes open on any call for cooling.
C. the vanes operate without binding.
D. the vanes are permanently set at 50%. - ✔✔ correct answer C. the vanes operate without binding.
On a 3 ton unit installation, the measure airflow equals 1550 CFM. What does this indicate?
A. Proper balancing
B. Low Airflow
C. Excess airflow
D. Improper balancing - ✔✔ correct answer C. Excess airflow(400cfm per ton, 3 ton=1200cfm)
Electronic type leak detectors typically have a push-button or knob for setting a reference refrigerant
level. This feature is useful for:
