Rheem
No Heating Call Reaching Equipment
Thermostat calls for heat but the furnace or heat pump does not start; fan may or may 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
Open W1 or Y1 control wire, Misconfigured system type (set to cool-only), Failed W1 output on thermostat, Blown low-voltage fuse on indoor board
How to Fix / Troubleshooting
Safety first: Turn off power to the indoor unit before accessing wiring.
Steps:
- Verify mode: Ensure the thermostat is set to 'Heat' and the setpoint is above room temperature.
- Check configuration: In installer settings, confirm the system type (heat pump vs conventional) and heat stages are correct.
- Inspect W1 wiring: Confirm the W1 (or W) wire is firmly connected at both thermostat and indoor board.
- Measure 24V at W1: With a heat call active, measure between W1 and C at the indoor board. If no voltage, suspect thermostat or wiring.
- Check low-voltage fuse: Replace a blown fuse only after checking for shorts in thermostat wiring.
- If voltage is present but no heat: The issue is in the furnace/air handler (limit switches, ignition, etc.) and should be diagnosed by a technician.
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Repair Difficulty
Hard
4/5
Required Part
W1 Heating Control Circuit
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