R-Pro › Field cases › Components
Sight Glass Bubble Formation
Likely causes
Low refrigerant charge — system refrigerant reduced due to leaks (most common cause)
Check: First check for leaks with electronic detector or soap bubbles → if no leak, check drier ΔT and subcooling
What to do: Repair leak → evacuate 30 min → recharge to specified weight (use scale) → verify bubbles disappear after operation
Drier clogging causing pressure drop after drier → flash gas generation
Check: Measure drier inlet/outlet temperature — ΔT ≥ 3°C indicates drier clog
What to do: Replace drier → evacuate → recharge → verify bubbles disappear
Minor bubbles normal with blended refrigerants (e.g., R-404A, R-407C) — avoid misdiagnosis
Check: Identify refrigerant type — R-404A/R-407C minor bubbles are normal. Confirm no leak and normal ΔT before concluding
What to do: No repair needed for minor bubbles in blended refrigerants. Do not overcharge based on misdiagnosis
Sight glass bubbles do NOT always mean low charge. Check drier ΔT and subcooling first. Minor bubbles are normal with blended refrigerants.
All 565 cases work offline in R-Pro, with error codes for 62 brands and P-T data for 108 refrigerants.
Open R-Pro →Related cases
- Liquid Refrigerant Entering Compressor (Flooded Start / Liquid Slugging)
- Compressor Motor Burnout / Ground Fault
- High Compressor Discharge Temperature (>107°C scroll, >120°C recip)
- Scroll Compressor Reverse Rotation — 3-Phase Miswiring
- Scroll Tip Seal Wear — Volumetric Efficiency Loss and Reduced Cooling Capacity
- Scroll Poppet Valve Fails to Close — Reverse Rotation Noise After Shutdown