Westinghouse Heat call not reaching furnace control

Furnace will not start when thermostat calls for heat, but fan-only mode works.

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.

Possible Causes

Broken W (heat) conductor in thermostat cable, Miswired thermostat terminals, Open safety in heat circuit (limit or rollout), Defective IFC heat relay

How to Fix / Troubleshooting

Safety: Turn off power before moving wires.

Steps:

At the furnace, verify that the W wire from the thermostat is securely connected to the W terminal on the IFC.
At the thermostat, confirm that the heat call wire is on the W terminal and that the thermostat is set to HEAT.
With power OFF, temporarily jumper R to W at the furnace. Restore power; if the furnace starts, the thermostat or cable is faulty.
If jumpering R to W does not start the furnace, a safety device or the IFC may be open; check limit and rollout switches and call a technician if unsure.

Repair Difficulty

Medium 3/5

Required Part

Wall Thermostat

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