CARO Refrigeration System Troubleshooting and Diagnosis

Question 1

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

Accepted Answer

Dirty or fouled condenser reducing heat rejection

Answer

Refrigerant undercharge

Answer

Expansion valve too far closed

Answer

Compressor valve failure

Question 2

Low suction pressure and low discharge pressure on an ammonia system most likely indicates what condition?

Accepted Answer

Undercharge of refrigerant or low refrigerant level

Answer

Overcharge of refrigerant

Answer

Dirty condenser

Answer

High ambient temperature

Question 3

A technician notices frost forming on the suction line all the way back to the compressor. What does this indicate?

Accepted Answer

Liquid refrigerant is flooding back to the compressor (liquid slugging risk)

Answer

Normal operation for a low-temperature system

Answer

The evaporator is operating efficiently

Answer

The system is overcharged with oil

Question 4

High discharge temperature with normal suction pressure on an ammonia compressor most likely indicates what problem?

Accepted Answer

High suction superheat or discharge valve inefficiency

Answer

Low refrigerant charge

Answer

Wet suction (liquid flood-back)

Answer

Low condenser water temperature

Question 5

What symptom would indicate that a thermostatic expansion valve (TXV) is stuck closed?

Accepted Answer

Low suction pressure, warm suction line, and starved evaporator

Answer

High suction pressure and flooding evaporator

Answer

High discharge pressure and normal suction pressure

Answer

Liquid returning to compressor

Question 6

Oil accumulation in the evaporator of an ammonia system causes which operational problem?

Accepted Answer

Reduced heat transfer efficiency and higher evaporating temperature

Answer

Increased refrigerant flow

Answer

Lower discharge pressure

Answer

Improved system lubrication