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View Full Version : Blower Not Turning On - Humming


justwhattodo
Jun 21, 2015, 07:42 AM
Last night we had several multi-second brownouts after which I noticed a slight change in the sound of our main HVAC unit (Bryant 350MAV 060120F). This morning I heard the unit trying to start the main blower and I just heard a humming sound which lasted about 5 - 10 seconds each time and then it stopped trying. It seemed to retry this every minute or so. Concerned that the motor would burn out, I turned off power to the unit. I removed the panel (which has already had the safety switch taped down) and tried to hand-turn the fan - it turns freely but stops immediately when I let go. I turned on the power and waited for the unit to start up. I heard the humming and tried to 'help it' by turning the fan but it was as if it was locked - i.e. the motor wouldn't allow the fan to turn either way.

Note:

* I did hear the relay or capacitor click as the motor was trying to start
* I feel heat coming off the back of the motor when it's humming
* The status light for the unit is solid red - "everything's fine" (well, it's not).
* With the unit not in AC mode, I did try "fan-only" mode and experienced the same (blower wouldn't start)

I do have a multimeter, don't have a hub puller.

Is this clearly a bad motor, bearings, etc.

I can pull the fan/motor unit if needed and/or jumper wires to try to get it run separately.

Recommendations?

ballengerb1
Jun 21, 2015, 08:10 AM
It sounds like the starter winding are shot, no fix other than replace the blower motor.

ma0641
Jun 21, 2015, 08:47 AM
Could possibly be a start capacitor. They are cheap and easy to replace. I'd start there first.

justwhattodo
Jun 21, 2015, 08:56 AM
OK, great, I'll try the capacitor first. Thx.

justwhattodo
Jun 22, 2015, 02:36 AM
OK- it wasn't the capacitor - I actually realized I could swap with the capacitor (same specs) I have on my second (smaller) unit and both capacitors are working fine. Based on that I've pulled the blower unit out - need to pick up a hub puller to extract the motor and find a replacement. Any recommendations on best places to find a replacement motor - is that something that Grainger would typically carry?

bitters
Jun 22, 2015, 05:52 AM
I have had a few that I just loosen the set screw and give it a good shake and the motor falls out. On the tough ones I heat them up, works every time.

justwhattodo
Jun 22, 2015, 03:31 PM
OK - so I've replaced the motor, re-inserted the blower assembly and wired everything up. When I start up the system, it starts up and runs for 3-5 seconds and then shuts down. The fan continues to rotate for many seconds - which it did not do with the old motor, but it still isn't running.

Next step? Thoughts?

justwhattodo
Jun 22, 2015, 03:45 PM
OK - actually - after letting it sit "on" (not running - just powered up), it's running like a champ. Thank you to all who helped with answers and guidance. I've learned a few new things in the past 24 hours.