HVACopediaAll brands · Refrigeration troubleshooting
Sight glass shows bubbles
What is going on
Possible causes and checks for: sight glass shows bubbles.
Likely causes
- Not necessarily low charge — liquid-line flash is normal on cap-tube systems
Check in this order
- Check charge by weight / superheat instead
More refrigeration guides
Take it to the job
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Source: General HVAC service practice — verify per model. Written in our own words; check the manual for your exact model.
For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.