American Standard No Call for Heat Reaching Control

Thermostat calls for heat but furnace does nothing, control board LED is on solid

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

Faulty thermostat, Broken W (heat) wire between thermostat and furnace, Misconfigured thermostat heat type, Loose W terminal screw on American Standard control board

How to Fix / Troubleshooting

Safety: Turn off power before moving thermostat wires.

Check thermostat settings:
- Ensure it is set to HEAT and temperature is above room temperature.
- Confirm system type (gas furnace) is correctly configured.
Test W circuit at furnace:
- With power off, remove the W wire and temporarily jumper R to W at the furnace board.
- Restore power; if the furnace starts, the thermostat or wiring is faulty.
Inspect wiring:
- Tighten W terminal screws at both thermostat and furnace.
- Repair any damaged cable.

Repair Difficulty

Medium 3/5

Required Part

Wall Thermostat

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