Originally Posted by kok328
and during the combustion cycle.
Now that you mention it, mine does this.
I've never looked for this before and I assumed that the hot exhaust gas would not need a motor to exhaust it.
BTW, an hour ago my furnace stopped working in our frigid temps. The symptoms seemed to change while I was probing around with a voltmeter so I thought my 30 YO furnace was disintegrating while I sat there.
It turns out it was corrosion on the control board connector and so it became mechanically sensitive.
Tomorrow I'll clean up this card edge connector and return the room heaters that we borrowed from the neighbors.
What a night.