Trane / American Standard · Furnace error code

Slow flashNormal: no heat call

Cross-checked Power off, standard tools

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Related diagnostic guides

Guide · Furnace

Furnace runs no heat (blower only or nothing)

Start with the board LED code, then work the call path: thermostat, 24 V, safeties, inducer, ignition, flame proving. Most no-heat calls end at a filter, a flame sensor, a pressure switch issue or gas being off.

5 steps ~45 minmoderate

Guide · Furnace

Blower runs constantly

Check the thermostat fan setting first, then whether the board is holding the blower on for a safety (open limit) or a stuck relay. On electric furnaces a stuck sequencer can do the same.

4 steps ~30 mineasy

Guide · Furnace

Burning smell when the heat first comes on

Dust settled on the heat exchanger or electric heat strips burns off at the first firing and fades within a few hours. A smell that lingers, or smells like plastic, rubber, hot wiring or gas, is not normal and needs diagnosis.

4 steps ~30 mineasy