FREE 313D Refrigeration Cycle Fundamentals Questions and Answers

Question 1

In a standard residential air conditioning system, what is the primary function of the evaporator coil?

Accepted Answer

To absorb heat from the indoor air, causing the refrigerant to boil.

Answer

The evaporator coil is located indoors and is responsible for absorbing heat from the indoor air. As the warm indoor air is blown across the cold evaporator coil, the liquid refrigerant inside absorbs this heat and boils, changing its state from a liquid to a low-pressure gas.

Question 2

A technician measures the refrigerant leaving the condenser and finds it is a high-pressure liquid at a temperature below its saturation point. What is this condition called?

Accepted Answer

Subcooling

Answer

Subcooling is the process of cooling a liquid refrigerant below its condensation/saturation temperature. This ensures that only liquid refrigerant enters the metering device, which is crucial for system efficiency and performance.

Question 3

Which of the following components is responsible for creating a pressure differential that allows the refrigerant to change from a high-pressure liquid to a low-pressure liquid?

Accepted Answer

Metering Device

Answer

The metering device (such as a TXV or capillary tube) creates a restriction in the flow of refrigerant. This restriction causes a significant drop in pressure, which in turn lowers the refrigerant's boiling point before it enters the evaporator.

Question 4

A residential AC system is running, and the compressor is functioning correctly. What is the expected state of the refrigerant as it enters the compressor?

Accepted Answer

Low-pressure, superheated vapor

Answer

The refrigerant leaves the evaporator as a low-pressure vapor. It should be slightly superheated, meaning its temperature is above its boiling point, to ensure no liquid refrigerant enters and damages the compressor.

Question 5

While diagnosing a system, a technician observes a very high superheat reading at the evaporator outlet. Which of the following is a potential cause?

Accepted Answer

Restricted liquid line filter drier

Answer

A restricted liquid line filter drier will starve the metering device of refrigerant. This causes the refrigerant to flash off too early in the evaporator, leading to an excessive amount of superheat as the vapor travels through the remainder of the coil.

(313D) Residential Air Conditioning Systems Mechanic Certification Practice Test

(313D) Residential Air Conditioning Systems Mechanic Certification Practice Test

FREE 313D Refrigeration Cycle Fundamentals Questions and Answers