small furnace fan

Sometimes this little black fan will emit a high pitch sound while spinning. If I slow down its spin by touching it with my finger, the pitch is lowered. I've had this Bryant furnace for 10 years and this just started happening. Could the fan be unbalanced? Any ideas on how to fix?

Update: The furnace is a Bryant Plus 80v


  • What model is this furnace? – ThreePhaseEel Mar 15 '17 at 2:34

Sounds more like a bearing going bad to me than a balance issue - unbalance is more often a vibration, and to become unbalanced the fan would either need to have a part fall off, or accumulate crud.

"Lifetime lubricated bearings" are a standard euphemism for "we prelubed and then provided no way to relube, so when it wears out from lack of lubrication, that's the lifetime of the fan" - i.e. I expect you are looking at replacement.

I know nothing about your specific furnace, but I know squealing fans pretty well.

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  • I agree that it is a bearing issue but many times the can be relubricated with a few drops of motor oil. If the old oil is sticky some WD40 will clean it up then some whatever motor oil. 5-50 weight, once the fibers pick up the oil it continues to wick until gone, but these type of bearings are usually only on light duty motors like this and fans. – Ed Beal Nov 27 '18 at 21:35

That is the "inducer" fan and motor. The fan is in the combustion exhaust stream to provide evacuation of combustion gasses. These do have a problem with noise and if it is the bearings of the motor, then the usual fix is to replace the fan/motor as a unit. See http://hvac-talk.com/vbb/showthread.php?184475-Loud-Vibrating-Inducer-Motor-Making-Me-Nuts!

My Carrier natural gas fired furnace has one which makes detectable noise until the main blower comes on and then noise from the inducer fan is drowned out by the main blower noise. Ours is original equipment and has been in service for 25 years, but there is a wide distribution in lifetime for this component.

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I've encountered this problem this week. Replaced the whole inducer assembly and seal that goes with it. Still made the same noise. Discovered that the flue stack wasn't connected properly, there were little air leaks at the connections that caused it to squeal, adjusted flue stack and taped up with aluminum tape and noise went away.

11-27-18 HVAC technician for 15 years 9 years miltary service

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