Troubleshooting Flashcards
7 cards from real RSES practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Troubleshooting flashcards as text
A commercial refrigeration system's discharge temperature is excessively high. Which of the following is NOT a likely cause?
Answer: Low ambient temperature at the condenser
Low ambient temperature at the condenser reduces head pressure and discharge temperature, making it an unlikely cause of excessive discharge temperature.
What symptom would a technician observe if a TXV is hunting (oscillating)?
Answer: Fluctuating suction pressure and superheat swinging above and below setpoint
A hunting TXV repeatedly over- and under-feeds refrigerant, causing suction pressure and superheat to oscillate continuously.
A technician checks a system and finds oil in the sight glass of the liquid line. What does this indicate?
Answer: Low refrigerant charge with oil becoming visible
When refrigerant charge is low, the remaining refrigerant carries proportionally more oil, making oil visible in the sight glass.
During a leak check using electronic leak detection, false positives are being triggered near a drain pan. What could cause this?
Answer: Cleaning solvents or certain drain pan treatments off-gassing halogen compounds
Some cleaning agents and drain pan treatments contain halogenated compounds that can trigger halide-based electronic leak detectors.
A technician measures 0°F superheat at the suction service valve of a running system. What immediate risk does this present?
Answer: Liquid refrigerant entering the compressor, risking mechanical damage
Zero superheat means liquid refrigerant is present in the suction line, and liquid entering the compressor can cause valve and piston damage.
Which of the following best describes 'flash gas' in the liquid line and why it is problematic?
Answer: Vapor formed when liquid refrigerant pressure drops below saturation, reducing expansion valve capacity
Flash gas occurs when liquid refrigerant pressure drops below its saturation point before the expansion device, reducing the valve's effective capacity.
A refrigeration technician finds that a compressor's amp draw is well below nameplate rating. What could this indicate?
Answer: Worn compressor valves reducing pumping efficiency
Worn or broken compressor valves reduce the work done per cycle, resulting in lower-than-normal current draw.