Compressors and Condensing Units Flashcards

What is the primary function of a compressor in a refrigeration cycle?

Answer: Increase the pressure and temperature of the refrigerant vapor

The compressor raises the pressure of the low-pressure refrigerant vapor, which also raises its temperature so heat can be rejected in the condenser.

Which type of compressor uses a piston moving back and forth inside a cylinder to compress refrigerant?

Answer: Reciprocating compressor

A reciprocating compressor uses pistons driven by a crankshaft to compress refrigerant through back-and-forth (reciprocating) motion.

What is the suction line in a refrigeration system?

Answer: The line carrying low-pressure vapor from the evaporator to the compressor

The suction line carries low-pressure refrigerant vapor from the evaporator back to the compressor inlet.

Which type of compressor uses two interlocking spiral-shaped scrolls to compress refrigerant?

Answer: Scroll compressor

A scroll compressor uses two interlocking spiral elements — one fixed and one orbiting — to trap and compress refrigerant.

What does a high-pressure lockout on a condensing unit protect against?

Answer: Excessively high discharge pressure that could damage the compressor

A high-pressure lockout switch shuts down the unit when discharge pressure exceeds safe limits, preventing compressor damage from excessive head pressure.

What is 'liquid slugging' in a compressor?

Answer: Liquid refrigerant entering the compressor and causing mechanical damage

Liquid slugging occurs when liquid refrigerant enters the compressor, which cannot compress liquid and sustains serious mechanical damage as a result.

On an air-cooled condensing unit, what is the purpose of the condenser fan?

Answer: Force outdoor air across the condenser coil to reject heat

The condenser fan moves ambient air over the condenser coil so the hot refrigerant vapor can reject its heat and condense into a liquid.