Refrigeration System Repair Flashcards
7 cards from real Air Conditioning Repair practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Refrigeration System Repair flashcards as text
A technician is diagnosing a system with low suction pressure, high superheat, and normal condenser performance. What is the most likely cause?
Answer: Restricted or underfeeding metering device
A restricted or underfeeding metering device starves the evaporator of refrigerant, causing low suction pressure and high superheat simultaneously.
What is the purpose of a crankcase heater on a compressor?
Answer: Prevent refrigerant from migrating into and diluting the compressor oil during off cycles
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.
When using an electronic leak detector on an HFC system, which type of sensor is most appropriate?
Answer: Infrared sensor
Infrared sensors are highly accurate for HFC refrigerants and are not destroyed by exposure to refrigerant the way heated diode sensors can be.
A system using a fixed orifice metering device shows high suction pressure in winter. What adjustment is typically required?
Answer: Replace with a TXV
Fixed orifice devices cannot modulate with changing conditions; replacing with a TXV allows proper refrigerant metering across varying outdoor temperatures.
What symptom would a technician observe if the reversing valve on a heat pump is stuck in the heating position?
Answer: No cooling in summer, heating works normally
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.
Which condition is indicated by oil streaks or staining around refrigerant line fittings and joints?
Answer: Refrigerant and oil leak at that location
Oil streaks at joints indicate refrigerant is leaking there, since refrigerant oil escapes along with refrigerant gas through any leak point.
A technician measures discharge superheat of 90°F. Normal discharge superheat is 50–70°F. What does this indicate?
Answer: Insufficient refrigerant or low suction pressure
Excessively high discharge superheat indicates the compressor is compressing very hot, low-density gas, typically caused by low refrigerant charge or high suction superheat.