Air Conditioner: Won’t engage
Won't engage on a air conditioner: Possible causes and checks for: won't engage.
How to fix won't engage: step by step
- Outdoor sensor ≤ cut-in (e.g. 65°F)
- Indoor needs cooling
- Humidity below limit (enthalpy), Y1 energizes damper relay/free-cooling damper
- Blower on
- Barometric relief damper opens. p.989 [963]
Safety: Gas, electrical and refrigerant work must be done by a licensed technician. Turn off power and gas before servicing, never bypass a safety control, and always follow the manufacturer's manual for your exact model.
If the unit shows an error code, look it up: Carrier Air Conditioner codes Goodman Air Conditioner codes KeepRite Air Conditioner codes Lennox Air Conditioner codes Trane Air Conditioner codes
Source: General HVAC service practice — verify per model. Written in our own words as a summary; always check the original manual.
General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.