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Inducer fan running when furnace is off


Premium Member
Mar 2, 2016
Ann Arbor
Model Number
-major brand-
More than 10 years
The other day I heard the inducer fan kick on, which surprised me because the system is Off. By the time I got downstairs it was not running. Finally caught it running. Turns on, runs for maybe 15 seconds (have not been able to time it), then turns off. Turned breaker off, then on. A day later it did it again. Repeated process, then a few hours later it did it again.

Indicator light is sold red.

If I turn on the furnace, and call for heat, everything operates normally. And, when it's done operating normally, the inducer fan doesn't turn on again by itself. Then we sit and watch and it doesn't do it.

Background - inducer fan 5 years ago. Power outage on Monday for 6 hours, came back on while we were out. No idea if it came on smoothly, or not, but no neighbors are complaining of issues.

I could only find one mention of this in my research so far, where it was the "quality" of electricity coming to the house, and they put in a relay that said the induction fan should not run unless there is a call for heat. I can't imagine this is our issue - why wouldn't both units do this.