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
What is the correct method for checking the refrigerant charge on a fixed-orifice system (piston or cap tube)?
Answer: Target superheat at the evaporator outlet using manufacturer charts
Fixed orifice systems are charged by targeting a specific superheat value (typically using a charging chart based on indoor/outdoor conditions) rather than subcooling.
A scroll compressor is running backwards due to incorrect wiring. What symptom will the technician observe?
Answer: Very low discharge pressure and high suction pressure with loud noise
A scroll compressor running in reverse produces very little compression, resulting in near-equal and abnormal pressures and often a distinctive noise.
What does the term 'refrigerant migration' refer to in a refrigeration system?
Answer: Refrigerant traveling to and accumulating in the compressor crankcase during the off cycle
Refrigerant migration occurs when refrigerant vapor moves toward the cold compressor oil during the off cycle, dissolving into the oil and causing compressor damage on startup.
A tech is adding refrigerant to a system and notices the manifold gauge hoses feel very cold. What does this indicate?
Answer: Liquid refrigerant is flowing through the hoses instead of vapor
Cold hoses during charging indicate liquid refrigerant is entering the system, which can damage the compressor; vapor charging or a liquid metering device should be used.
Which EPA regulation governs the handling, recovery, and recycling of refrigerants used in stationary HVAC equipment?
Answer: Section 608 of the Clean Air Act
Section 608 of the Clean Air Act establishes technician certification requirements and regulations for refrigerant handling in stationary refrigeration and air conditioning equipment.
What is the likely cause when a system's high-pressure switch trips repeatedly during hot summer days but not in moderate weather?
Answer: Dirty or restricted condenser coil reducing heat rejection
A dirty condenser coil restricts airflow and reduces the system's ability to reject heat, causing discharge pressure to rise above the high-pressure switch cutout on hot days.
When brazing refrigerant lines, why is it important to flow dry nitrogen through the tubing during the brazing process?
Answer: To prevent internal oxidation scale that could contaminate the refrigeration system
Flowing nitrogen through tubing during brazing displaces oxygen and prevents copper oxide scale formation inside the lines, which can clog metering devices and damage compressors.