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 does a high subcooling reading combined with high discharge pressure most likely indicate?
Answer: Non-condensables in the system
Non-condensables such as air in the system raise discharge pressure and subcooling because they occupy condenser space without condensing.
When recovering refrigerant from a system, the technician must use equipment certified to which standard?
Answer: SAE J2788
SAE J2788 certification is required for refrigerant recovery/recycling equipment used on motor vehicle AC systems; EPA Section 608 requires similar certification for stationary systems.
A tech notices the evaporator coil is freezing up only at the inlet. What is the most likely cause?
Answer: Metering device feeding too much refrigerant
When the metering device feeds excessive refrigerant, it floods the evaporator inlet, causing ice formation at the entry point where liquid refrigerant accumulates.
What is the minimum evacuation level (microns) typically required before recharging a residential air conditioning system?
Answer: 500 microns
Industry standard requires pulling the system down to 500 microns or below to ensure adequate moisture and air removal before charging.
A compressor has a burnt motor winding. After replacing it, what additional step is critical before restarting?
Answer: Flushing the system to remove acid and debris
A burnt motor leaves acid contamination that must be flushed out and a liquid-line suction filter-drier installed to prevent damage to the new compressor.
Which type of oil is used in systems charged with R-410A refrigerant?
Answer: Polyol ester (POE) oil
POE oil is required in R-410A systems because it is miscible with HFC refrigerants and properly lubricates the compressor throughout the system.
What does a negative superheat reading at the evaporator outlet indicate?
Answer: Liquid refrigerant is leaving the evaporator
Negative superheat means the refrigerant temperature at the evaporator outlet is below saturation temperature, indicating liquid refrigerant is leaving the coil.