NATE AC SERVICE CERTIFICATION EXAM
Questions and Answers
1.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
ANS: D. 6 pounds
15ft - 25ft = 10ft x .6 = 6 ounces
5 pounds + 10 ounces + 6 ounces
5 pounds + 16 ounces = 6 pounds
2.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.
, ANS: C. reduce oxidation.
3.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.
ANS: A. be mounted above flood level.
4.The component used to reduce sound transmission and
prevent water leaks on a rooftop air conditioner packaged unit
installation is the:
A. curb gasket.
B. silicone caulk.
C. roof flashing.
D. roofing tar.
ANS: A. curb gasket.
5.Return air leakage in a hot attic will:
A. Increase capacity
B. Decrease capacity
C. Increase airflow
,D. Decrease airflow
ANS: B. Decrease capacity
6.An air conditioner refrigerant circuit should be evacuated to a
minimum of:
A. 0 microns.
B. 200 microns.
C. 500 microns.
D. 1200 microns.
ANS: C. 500 microns.
7.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
ANS: D. Carbon Dioxide
8.The subcooling method for checking charge is generally used
on air condi- tioners with what type of metering?
A. Only externally equalized thermostatic expansion valves
, B. Any thermostatic expansion valve
C. Piston type
D. Any fixed metering device
ANS: B. Any thermostatic expansion valve
9.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.
ANS: C. a vapor barrier.
10.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%.
ANS: C. the vanes operate without binding.
11.On a 3 ton unit installation, the measure airflow equals
1550 CFM. What does this indicate?
Questions and Answers
1.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
ANS: D. 6 pounds
15ft - 25ft = 10ft x .6 = 6 ounces
5 pounds + 10 ounces + 6 ounces
5 pounds + 16 ounces = 6 pounds
2.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.
, ANS: C. reduce oxidation.
3.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.
ANS: A. be mounted above flood level.
4.The component used to reduce sound transmission and
prevent water leaks on a rooftop air conditioner packaged unit
installation is the:
A. curb gasket.
B. silicone caulk.
C. roof flashing.
D. roofing tar.
ANS: A. curb gasket.
5.Return air leakage in a hot attic will:
A. Increase capacity
B. Decrease capacity
C. Increase airflow
,D. Decrease airflow
ANS: B. Decrease capacity
6.An air conditioner refrigerant circuit should be evacuated to a
minimum of:
A. 0 microns.
B. 200 microns.
C. 500 microns.
D. 1200 microns.
ANS: C. 500 microns.
7.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
ANS: D. Carbon Dioxide
8.The subcooling method for checking charge is generally used
on air condi- tioners with what type of metering?
A. Only externally equalized thermostatic expansion valves
, B. Any thermostatic expansion valve
C. Piston type
D. Any fixed metering device
ANS: B. Any thermostatic expansion valve
9.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.
ANS: C. a vapor barrier.
10.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%.
ANS: C. the vanes operate without binding.
11.On a 3 ton unit installation, the measure airflow equals
1550 CFM. What does this indicate?
