Compressor & Component Diagnostics Flashcards
7 cards from real CFC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Compressor & Component Diagnostics flashcards as text
A technician diagnoses a compressor with liquid slugging damage. Which internal component is most commonly damaged first by this condition?
Answer: Suction and discharge valve reeds
Valve reeds are thin, flexible metal components that fracture almost immediately when subjected to the hydraulic shock of liquid refrigerant or oil slugging.
A system equipped with a crankcase pressure regulator (CPR) valve at the compressor suction uses it primarily to:
Answer: Limit the suction pressure to protect the compressor motor from overloading at startup
A CPR valve limits suction pressure entering the compressor to prevent motor overload during pull-down when suction pressure is initially very high.
Which condition would cause a compressor discharge temperature to exceed 300°F (149°C)?
Answer: High compression ratio combined with high suction superheat
High compression ratio (high head pressure) combined with high suction superheat produces extremely high discharge temperatures because both factors increase the temperature of the compressed gas.
A technician performs a pump-down test and the system reaches the low-pressure cutout in an unusually short time. This indicates:
Answer: The system is undercharged with refrigerant
An undercharged system has insufficient refrigerant mass to maintain evaporator pressure, causing rapid pump-down to the low-pressure cutout.
When diagnosing a compressor with a suspected internal leak across the discharge valve, which field measurement best confirms this?
Answer: Compressor off-cycle pressure equalization occurring faster than normal
A leaking discharge valve allows high-side pressure to bleed back to the low side during the off-cycle much faster than the normal equalization time, confirming internal bypass.
A compressor on a CFC-11 centrifugal chiller experiences surge repeatedly at part-load conditions. What is the primary cause of compressor surge?
Answer: The pressure differential exceeding the compressor's ability to produce flow at reduced speed
Surge occurs when the pressure differential across a centrifugal compressor exceeds its ability to maintain stable flow at reduced capacity, causing cyclical flow reversal.
After recovering CFC refrigerant from a system with a burned-out compressor motor, what additional step is required before recharging with virgin or reclaimed refrigerant?
Answer: The system must be dehydrated, acid-flushed, and the recovered refrigerant sent for reclamation to ARI-700 standards
A burnout contaminates refrigerant with acid and carbon, requiring full system decontamination and sending recovered refrigerant to a certified reclaimer to meet ARI-700 purity standards before reuse.