RSES Troubleshooting 2

Question 1

A refrigeration system has high discharge pressure and high suction pressure. What is the most likely cause?

Accepted Answer

Overcharge of refrigerant

Answer

An overcharge of refrigerant raises both suction and discharge pressures above normal operating levels.

Question 2

A technician finds oil accumulation in the evaporator of a low-temperature system. What is the most probable cause?

Accepted Answer

Insufficient refrigerant velocity to return oil

Answer

At low temperatures, refrigerant vapor velocity may be too low to carry oil back to the compressor, causing oil to accumulate in the evaporator.

Question 3

During operation, a system's compressor cycles on and off rapidly (short-cycles). Which condition is the LEAST likely cause?

Accepted Answer

Dirty condenser coil

Answer

A dirty condenser coil raises discharge pressure but does not typically cause rapid short-cycling on the low-pressure control.

Question 4

A walk-in cooler compressor runs continuously but the box temperature never reaches setpoint. Suction pressure is low and discharge pressure is normal. What should be checked first?

Accepted Answer

Refrigerant charge (undercharge)

Answer

Low suction pressure combined with continuous compressor operation and warm box temperature strongly suggests a refrigerant undercharge.

Question 5

What does a frost pattern that stops midway through an evaporator coil typically indicate?

Accepted Answer

Partially blocked or malfunctioning expansion device

Answer

A frost pattern ending midway indicates refrigerant is fully evaporating before the end of the coil, suggesting a restricted or undersized expansion device.

(RSES) Refrigeration Service Engineers Society Certification Practice Test

(RSES) Refrigeration Service Engineers Society Certification Practice Test

RSES Troubleshooting 2