CFC Compressor & Component Diagnostics 5

Question 1

A technician diagnoses a compressor with liquid slugging damage. Which internal component is most commonly damaged first by this condition?

Accepted Answer

Suction and discharge valve reeds

Answer

Valve reeds are thin, flexible metal components that fracture almost immediately when subjected to the hydraulic shock of liquid refrigerant or oil slugging.

Question 2

A system equipped with a crankcase pressure regulator (CPR) valve at the compressor suction uses it primarily to:

Accepted Answer

Limit the suction pressure to protect the compressor motor from overloading at startup

Answer

A CPR valve limits suction pressure entering the compressor to prevent motor overload during pull-down when suction pressure is initially very high.

Question 3

Which condition would cause a compressor discharge temperature to exceed 300°F (149°C)?

Accepted Answer

High compression ratio combined with high suction superheat

Answer

High compression ratio (high head pressure) combined with high suction superheat produces extremely high discharge temperatures because both factors increase the temperature of the compressed gas.

Question 4

A technician performs a pump-down test and the system reaches the low-pressure cutout in an unusually short time. This indicates:

Accepted Answer

The system is undercharged with refrigerant

Answer

An undercharged system has insufficient refrigerant mass to maintain evaporator pressure, causing rapid pump-down to the low-pressure cutout.

Question 5

When diagnosing a compressor with a suspected internal leak across the discharge valve, which field measurement best confirms this?

Accepted Answer

Compressor off-cycle pressure equalization occurring faster than normal

Answer

A leaking discharge valve allows high-side pressure to bleed back to the low side during the off-cycle much faster than the normal equalization time, confirming internal bypass.

(CFC) Chlorofluorocarbon Certification Practice Test

(CFC) Chlorofluorocarbon Certification Practice Test

CFC Compressor & Component Diagnostics 5