Air Conditioning Repair Refrigeration System Repair 4

Question 1

A technician is diagnosing a system with low suction pressure, high superheat, and normal condenser performance. What is the most likely cause?

Accepted Answer

Restricted or underfeeding metering device

Answer

A restricted or underfeeding metering device starves the evaporator of refrigerant, causing low suction pressure and high superheat simultaneously.

Question 2

What is the purpose of a crankcase heater on a compressor?

Accepted Answer

Prevent refrigerant from migrating into and diluting the compressor oil during off cycles

Answer

A crankcase heater keeps the compressor warm during the off cycle to prevent refrigerant from migrating and mixing with the oil, which could cause slugging on startup.

Question 3

When using an electronic leak detector on an HFC system, which type of sensor is most appropriate?

Accepted Answer

Infrared sensor

Answer

Infrared sensors are highly accurate for HFC refrigerants and are not destroyed by exposure to refrigerant the way heated diode sensors can be.

Question 4

A system using a fixed orifice metering device shows high suction pressure in winter. What adjustment is typically required?

Accepted Answer

Replace with a TXV

Answer

Fixed orifice devices cannot modulate with changing conditions; replacing with a TXV allows proper refrigerant metering across varying outdoor temperatures.

Question 5

What symptom would a technician observe if the reversing valve on a heat pump is stuck in the heating position?

Accepted Answer

No cooling in summer, heating works normally

Answer

If the reversing valve is stuck in heating mode, the system will heat in both summer and winter, providing no cooling when switched to cooling mode.

Air Conditioning Repair Practice Test

Air Conditioning Repair Practice Test

Air Conditioning Repair Refrigeration System Repair 4