Schneider Electric
No Cooling Call from Thermostat
Cooling does not start even though the thermostat is set to Cool and the room is above setpoint.
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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
Thermostat mode not correctly set to Cool, Loose or broken Y (cooling) wire, Incorrect heat pump configuration (reversing valve setting), Failed cooling output relay
How to Fix / Troubleshooting
Safety: Turn off power to the HVAC system before touching wiring.
Steps:
- Ensure the thermostat is in Cool or Auto mode and the cooling setpoint is below room temperature.
- Remove the thermostat and verify that the cooling call wire is firmly attached to the Y or COOL terminal.
- At the air handler or condenser control board, check for 24 VAC between R and Y when the thermostat is calling for cooling. If there is no voltage, the thermostat is not sending a cooling call; replace the thermostat.
- If voltage is present but the condenser does not start, the issue lies in the HVAC equipment (contactor, capacitor, compressor) and requires an HVAC technician.
- For heat pump systems, verify that the O/B reversing valve setting in the thermostat matches the equipment requirements.
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Repair Difficulty
Medium
3/5
Required Part
Cooling Call Output (Y Terminal) on Thermostat
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