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ragrawal · Sep 5, 2007, 02:57 PM

Hi
Why does my gas-furnace not run? (fan-blower won't start)

I could not see any blown fuses or circuit-breakers; power-switch is on; I ignited the pilot-light and turned the temp to 90 in thermostat - but fan-blower did not start at all, even after waiting for 10 min; I measured voltage at fan terminals and it was practically zero (bleed 0.1v)

Later, I connected power directly to fan-blower and it started running; could it be the control-board malfunction?? Or is it thermostat problem

Thanks
Rajat

hvac1000 · Sep 5, 2007, 03:23 PM

Yes it could be a control board or a relay. I would check for a defective relay first. Boards are expensive. Try tracking down the voltage for the motor and see where it stops at. That will be the defective part.

labman · Sep 5, 2007, 04:47 PM

There is a sticky at the top of this forum. In it, it lists the sequence a gas furnace goes through in starting. Check each step. Post back with what you find.

ragrawal · Sep 5, 2007, 05:07 PM

Originally Posted by labman

There is a sticky at the top of this forum. In it, it lists the sequence a gas furnace goes through in starting. Check each step. Post back with what you find.

Did you mean the following:
How do I know if the problem is in the thermostat?
Or 'Sequence of operation'

Thanks
Rajat

labman · Sep 5, 2007, 08:01 PM

If the inducer blower starts, the thermostat is working correctly. Follow the rest of the sequence. If the inducer doesn't start, then go to the thermostat test.