Trane Furnace Fan won't start

Old 10-19-09, 10:32 AM
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Trane Furnace Fan won't start

Hi guys,

I have an older Trane gas furnace model TUS080A936A1. When I turned on the heat this season the gas lights but the fan doesn't come on. The gas will run for a couple of minutes and then shut down I assume with over temp switch. The fan will work when I set it to "on" with the thermostat.
Does anyone know if Trane uses a time delay or temp sensor to delay the fan coming on and shutting off? Any schematics or part numbers would help too..Thanks!!
Old 10-19-09, 05:28 PM
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How did it used to behave when it used to work correctly? Can you remember if you first had fire first, and then the blower would come on in about 1 minute or so? If so, it likely works on a temperature switch. And also different circuitry is used compared to the fan ON circuit. When you set the stat to fan ON, there is no delay, compared to the AUTO circuit.

Besides something amiss in the circuit say right on the board, or with a fan switch on or off the board, it could also be a fan speed winding that is out- if- you have central air a/c. If you do, and if you have a multi-speed fan...... follow the fan wires plugged into a control board, reverse the wire that is on HEAT, with the one that is on COOL, and see if it works then.

My advice is generic, not knowing your particular furnace insides, right off the top of my head. Just some general theory, that may help you.

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