NATE Air Conditioning

Question 1

What refrigerant is most commonly used in modern residential air conditioning systems in the US?

Accepted Answer

R-410A

Answer

R-410A replaced R-22 as the standard residential AC refrigerant due to R-22's ozone-depleting properties.

Question 2

What is the purpose of the metering device in a refrigeration circuit?

Accepted Answer

Reduce refrigerant pressure and control flow into the evaporator

Answer

The metering device reduces high-pressure liquid refrigerant to low-pressure liquid/vapor, controlling flow into the evaporator.

Question 3

Which component in an air conditioning system is responsible for rejecting heat to the outdoors?

Accepted Answer

Condenser

Answer

The condenser releases heat absorbed from the indoor air to the outdoor environment.

Question 4

What does superheat measure in a refrigeration system?

Accepted Answer

Temperature rise of vapor above the saturation point at a given pressure

Answer

Superheat is the number of degrees the refrigerant vapor temperature exceeds the saturation temperature at that pressure.

Question 5

What is the typical target evaporator superheat range for a fixed-orifice metering device system?

Accepted Answer

10–18°F

Answer

A fixed-orifice system typically targets 10–18°F of superheat at the evaporator outlet for proper refrigerant feed.

NATE - North American Technician Excellence Practice Test