I have a Winchester Model GM8S060A12DN11B downflow furnace/ac.

A couple of weeks ago, I came home to notice an awkwardly loud noise coming from the return vent when the fan is blowing. (Mind you, this is with the AC on not that I think this makes a difference)

Over the past two weeks, it has gotten progressively worse. Upon startup it is most commonly the loudest, and eases down after it gets running for a while. But it is still really loud.

It is NOT a high pitch sound, but sounds like a bearing going out. My initial assumption is that the motor is going in the fan unit, but I have not taken it apart to diagnose yet. I'll be disassembling today.

Just wanted to know if anyone was familiar with this type of situation and what possible parts may have failed. Any tips are much appreciated. I'll have to order the motor online to save a few dollars to fix it, so I'll re-assemble today after inspection. Any way of a tell tale sign that the motor bearings are shot?

Thanks in advance!

 

Be sure to check the squirrel cage assembly. The noise might be coming from that rather than the motor itself. Assuming that there is a belt connecting the motor to the squirrel cage, remove the belt and turn on the motor. If you hear the noise, it's the motor. If you don't hear the noise, then it's possibly the squirrel cage bearings/bushings. On my old furnace (~15 years ago), I had to replace the squirrel cage bushings. I got the replacement parts from Grainger.

 

It's a direct drive, no belt.

The main shaft of the motor is the "axle" for the squirrel cage.

 

Depending upon how bad the bearings are, sometimes you can feel a "roughness" when you try to turn the shaft. However, since you have a direct drive motor (my new York furnace is similar), assuming the squirrel cage isn't rubbing on anything, the motor seems to be just about the only possibility.

 

Thanks! That's what my thoughts were too. I wanted to double check the main shaft and the bolt that holds it and to see if the fan was rubbing on the housing possibly somewhere before purchase. Sadly, I don't know where to get one locally, and I'll have to order it.

Appreciate the help!

 

it was the motor. replaced it with a high efficiency unit from the local hardware store.

 

Glad to hear that you got the problem solved, and thanks for reporting back.