HVACopediaAll brands · Air conditioner troubleshooting
No cooling
What is going on
Possible causes and checks for: no cooling.
Likely causes
- All zones to cool 5°F below room (master-slave: system switch to cool)
- After
- Min check contactor. If not: 24 Vac Y–C at panel output (blown panel fuse?)
- Stat side 24 V Y–C, 0 V R–Y, 24 V R–W confirms panel/stats OK
- At condenser: 24 V across contactor coil, line voltage at disconnect/top of contactor, 24 V at control terminals. pp.1002–1003 [976–977]
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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.