USCG Exam PracticeRefrigeration and air conditioning
A sight glass in the liquid line between the receiver and the metering device shows a steady stream of bubbles. What does this most likely indicate?
- A. The system is overcharged and liquid is backing up into the condenser
- B. The compressor is running at reduced capacity due to cylinder unloading
- ✓ The system is undercharged or there is a restriction upstream of the sight glassCorrect
- D. Non-condensable gas has collected in the evaporator, reducing heat transfer
Why C is correct
NAVEDTRA 14075 §6-3 states that a sight glass showing bubbles indicates the system is undercharged or restricted, while a solid liquid column indicates a fully charged system. Non-condensable gas collects in the condenser and receiver, not the evaporator, and an overcharge would produce a solid liquid line.
Cited:NAVEDTRA 14075 §6-3