HVACopediaAll brands · General troubleshooting
Monthly check
What is going on
Possible causes and checks for: monthly check.
Likely causes
- Sight glass 1/3–1/2
- High → drain
- Low but visible → add
- None visible or pressure high → shut off, cool, then add. Relief lever must discharge
- LWCO must trip on drain
More general 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.