Cool Not Responding
Honeywell Home
Failed Cooling Call from Thermostat to Equipment
App or thermostat shows 'Cool Not Responding' and AC does not run
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Loose Y (cool) wire, Tripped float switch or condensate safety, Blown low‑voltage fuse, Faulty outdoor unit contactor or control board
How to Fix / Troubleshooting
Safety: Turn off power to both the furnace/air handler and outdoor condenser before working on wiring.
- Check thermostat settings: Confirm the thermostat is in Cool mode with a setpoint below room temperature.
- Inspect Y terminal wiring: At the thermostat and furnace board, ensure the Y (or Y1) wire is secure. Tug gently to confirm it is clamped.
- Check condensate safety switch: If your system has a float switch in the drain pan, a full pan can open the Y circuit. Clear the drain line and reset the switch.
- Inspect low‑voltage fuse: Replace any blown fuse on the furnace control board after checking for shorts in the thermostat cable.
- Bypass test (advanced): With power off, jumper R to Y at the furnace board. Restore power; if the outdoor unit starts, the thermostat or wiring is suspect. If not, the outdoor unit contactor, control board, or safety circuit may be faulty and requires a technician.
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Repair Difficulty
Hard
4/5
Required Part
Outdoor Condenser Contactor
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