Schneider Electric
No Heat Call from Thermostat
Thermostat powers on but does not call for heat even when room temperature is below 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
Incorrect system mode (set to Cool or Off), Misconfigured system type (heat pump vs conventional), Loose heating call wire (W or HEAT terminal), Failed heating output relay on thermostat
How to Fix / Troubleshooting
Safety: Turn off power to the HVAC system before adjusting wiring.
Steps:
- Verify on the thermostat screen that the mode is set to Heat or Auto and that the setpoint is above the current room temperature.
- Enter installer settings and confirm the correct system type (e.g., boiler, furnace, heat pump) is selected according to the Schneider Electric manual.
- Remove the thermostat and check that the heating call wire is securely connected to the correct terminal (often W, W1, or HEAT).
- With power restored and a heat call active, check for 24 VAC between R and W at the air handler or boiler control board. If there is no voltage, the thermostat may not be closing the heating relay; replace the thermostat.
- If there is voltage at the control board but the heater does not start, the issue is in the HVAC equipment, not the thermostat; contact an HVAC technician.
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Repair Difficulty
Medium
3/5
Required Part
Heating Call Output (W Terminal) on Thermostat
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