Scott dev

One of the bags on the dust collector fell off last night and filled my shop with dust. I turned on the exhaust fan to clear the dust out and I think maybe I created a negative presure in the building. Since then my furnace won't start. I have a Carrier weathermaker 8000, but it doesnt appear to have the codes. When I turn it on, the fan runs for awhile, then it stops and the small exhaust fan comes on and then thats it, the small exhaust fan just keeps running and nothing else happens. It does't even try to lite.
Any ideas, thanks.

Celtic

Is there a pilot light?

Check if the dust didn't create a smother condition where the pilot was extinguished.

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crmont

The pressure switch is not closing when the little blower starts. A little rubber hose connects the two. Remove the hose at the little blower and push a little allen wrench through the port. The main blower starts first becouse power is restored while the thermostat is calling for heat. (it's tries to cool the heat exchanger in the event of a quick power failure)

mdshunk

Cycle the power to the unit to reset the board, and see if it fires up now. I suspect that your unit "locked out" and won't even try any more.

Scott dev

thanks for info so far, the furnace does't have a pilot light, I tried shutting the power off quite a few times for various lenghts and that didn.t seem to make a difference. I will try the blower thing later when I get home. thanks.

Scott dev

Thanks guys,
I found a small sensor above the pressure switch ,almost in the vent had tripped, I reset it and she works great again. Thanks again.

snapperhead

if the supply fan was running when the bag broke you might of cycled some dust thru the unit,check that filter and the rounds on the fan squirrel cage that all are clear and clean