Way off topic! I'm having furnace blower motor issues..need some help

[blasterfied]

I have a American Standard freedom 90 gas furnace.

Lately the blower motor makes a buzzing sound as it ( blower) begins to run, then the buzzing stops and the blower runs smooth as it always did. Could this be a bad motor condenser causing insufficient voltage at start-up? I'm not much of a HVAC expert. But I can work on them if I have to. The diagnostics part gets challenging.

 

[Herpderplol]

Could it be rattling? A mount loose somewhere?

Or bad bearings?

We have a small blower on a stove and it rattles because the screw holes dont line up. And my moms car blower squeels a little because of bad bearings

 

[blasterfied]

No rattle and no restriction on the motor. It's a direct drive and the motor and/or squirrel cage spins effortlessly. Once the blower motor runs post buzz, it's whisper quiet

 

[dirtysquared]

I mostly deal with big motors (100hp+). But when there is a buzzing at startup, then stops when it warms up, Its usually something in the motor starter or a thermal overload protector getting weak.

Sometimes a buzz is a lack of power also. maybe check it to see if its getting the correct amount of power.

I mostly deal with 3 phase Pumps and motors though. Thought I might be of some help?

 

[kevinsranger]

it could be the startup capacitor going bad too, you would need specs, an multimeter and basic tools.

try blowing it out with compressed air, either from a compressor or from the computer "air in a can", sometimes dust and dirt can build up in there and act as a conductor and cause funky electrical issues

 

[blasterdemon7]

I would check the fan blades for dust build up.

 

[blasterfied]

I took the blower motor out completely and blow inside the motor, it was dusty but not too bad. I checked for play in the motor shaft, found little to no play. After reassembly I turned the blower on. It still hums but not nearly as bad or as loud. At times I never hear the motor start-up. We bought the house 8 1/2 years ago, and this is only major problem I have had.

I remember this sound when I used a potentiometer on a 1/3HP 115VAC motor not designed for one. On a low setting it hummed loudly and took longer to start-up. So I figured the issue with the blower motor was I had a drop in voltage at the motor, but it checks out fine.

 

[Blaaster]

It is quite possible that the condenser/capacitor is becoming poor and not doing its job of smoothing out the supply.

If the buzzing is at twice the AC frequency, then I would suspect either a poor condenser/capacitor or a tired starting circuit