HVACopediaAll brands · General troubleshooting
No heating
What is going on
Possible causes and checks for: no heating.
Likely causes
- All stats to heat 5°F above room
- Dampers all open after
- Min
- Stat side 0 V R–W, 24 V R–Y, 24 V R–C
- System side 24 V W–C, 0 V Y–C, 24 V R–C
- If 24 V W–C and no heat → furnace (ignition, gas flow, safeties, pressure switches). p.1003 [977]
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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.