System info-
MODEL: GMH950905
Capacitor: 370VAC 15microf

So after reading through the posts here and watching some youtube videos, I thought for sure this unending buzzing sound when the blower motor was stopped on regular heat settings had to be the CAPACITOR. I replaced it with the 370/440VAC rated new one. However, after replacing it the motor still stops after 3 minutes or so. It sounds like its "trying" and the buzzing sound returns, but simply stops and the whole system turns off.

Fan seems to spin when system is off. I can push it manually and it turns about 180degrees. The fan does vibrate what I would think is A LOT, but I'm no expert on what is a normal amount of vibration. I dont have a way to "grease" the fan motor (if this type even has zerks).

I am wondering if my problem is with my control board or the motor or something I'm missing. I am fairly mechanical but not an HVAC tech. I haven't dug my meter out yet to start troubleshooting the board.

 

Welcome to the forums.

If you thought this was a board problem....... you'd watch the AC voltage to the blower motor. There are usually two blower speeds connected..... high for cooling and a medium for heat. You'd connect your meter to the common neutral and the heating terminal checking for 120vAC.

However, the problem you are describing is worn blower motor bearings. Typically the bearing on the blower wheel side of the motor is severely worn from the weight of the blower wheel. You can check by lifting the blower wheel up. There should be no play.

There are no grease or oil fittings on most of the blower motors. Your option is to replace it. They offer many subs for most blower motors. Be aware that every motor requires a certain sized capacitor. A replacement motor may not use the same size you already have and need a new one.

 

See the video here. I think the vibration at about 3 - 4 minutes is confirming your thoughts. https://youtu.be/iBb9if0jQ5A

 

I just checked and there doesnt seem to be any blower motor "endplay" in the bearings - pushed multiple directions, no give. hmmm.

 

I recognize that sounds instantly...... bead bearings.

It may be hard to feel the play with the unit in place. When you take it out it becomes much easier.
That motor won't run much longer.

 

Thanks so much for the quick replies.

 

We had a tech come out and he was able to pinpoint it as the blower motor. He has replaced/upgraded.

 

Same problem in my case as well - blower motor gave up. I am just adding my experience for others looking for help. Two months ago happened to catch, that the blower does not spin and make. In this case first you want to do is by hand (pwr off of course) to try spin the fan. In my case was blocked. I opened and lubricated the bearings on both sides and was back in business in no time. However, it was not the same anymore. There was always a little noise like out of balance wheel. After three months, it gave up again. This time the fan was spinning just fine, but the motor did not go on anymore after it is switched and attempted to start. Ordered new replacement, next day delivered and replaced; Cap was not bad but changed as well. Meanwhile I switched the blower to different speed to gave me a run for another 12h, before I got the replacement. Old furnaces (06) have on Park two more speeds to run on.... with the new motoe run as a charm so far.