Free Air Conditioning Repair Refrigeration Cycle Principles Questions and Answers

Question 1

In a properly operating refrigeration cycle, what is the state and pressure of the refrigerant as it enters the compressor?

Accepted Answer

Low-pressure, low-temperature superheated vapor

Answer

The refrigerant enters the compressor as a low-pressure, low-temperature superheated vapor. The evaporator's job is to absorb heat, causing the refrigerant to boil from a liquid into a vapor. Superheat is additional heat absorbed after it has fully vaporized, which ensures no liquid enters and damages the compressor.

Question 2

A technician measures a system's subcooling and finds it to be significantly higher than the manufacturer's specification. Which of the following is the most likely cause?

Accepted Answer

A refrigerant overcharge

Answer

High subcooling indicates that the refrigerant is being cooled in the condenser more than necessary. This is typically caused by an overcharged system, where excess refrigerant backs up in the condenser, remaining in its liquid state for longer and thus losing more heat.

Question 3

What is the primary function of the metering device in the refrigeration cycle?

Accepted Answer

To create a pressure drop, which lowers the refrigerant's boiling point

Answer

The metering device (such as a TXV or capillary tube) creates a restriction that causes a significant drop in pressure. This pressure drop lowers the refrigerant's saturation temperature (boiling point), allowing it to absorb heat and boil in the evaporator.

Question 4

A technician is diagnosing a residential air conditioning unit that is not cooling effectively. The suction line leading to the compressor is warm to the touch and the superheat is measured to be excessively high. What is a probable cause for these symptoms?

Accepted Answer

The system is undercharged or has a restriction.

Answer

Excessively high superheat means the refrigerant vapor is gaining too much heat after boiling in the evaporator. This is often caused by an undercharge of refrigerant or a restriction (like a clogged filter drier or kinked line), which starves the evaporator and causes the refrigerant to vaporize too early in the coil.

Question 5

Which of the following describes the process occurring within the condenser coil?

Accepted Answer

High-pressure vapor refrigerant rejects heat and condenses into a liquid.

Answer

The condenser receives high-pressure, high-temperature vapor from the compressor. As outdoor air is blown across the condenser coils, the refrigerant rejects heat to the ambient air, causing it to desuperheat and then condense into a high-pressure liquid.

Air Conditioning Repair Practice Test

Air Conditioning Repair Practice Test

Free Air Conditioning Repair Refrigeration Cycle Principles Questions and Answers