The one I obtained was an industrial style, designed specifically for the job intended, works fine.

 

Couple days ago, fan quit, uh oh. Noticed it was hotter upstairs.
When powered on motor buzzes. Spin fast by hand it runs.
Takes some force to spin it up as it feels magnetized. Spins free with power off.

I ordered two new 7.5 capacitors.
Do you think the old run cap failed?
The old run cap is more than 15 yrs old. Maybe even 20. I pulled it out of an old gas furnace I bought long time ago which I never used just to get this replacement motor for the fan to run.

What I did like is the thermal protection on GE motor works. Yesterday when going into attic, power was on, no motor hum.
Turned off power to motor.
This am turned on power, motor hums, looks like barely rotates a few degrees. Means to me thermal protection works.
Noticed when powered on and it hums the attic light very subtly dimmed, motor drawing lot power.
Looked at copper windings, they are shiny bright, bearings not worn.

I ohmed the low speed yellow wire to white wire, still good about 3.5 ohms, tells me the coils are good.

 

Is this a different fan motor? Capacitors do fail eventually. AT least it looks that way. And some times it appears that some fan motors do not use capacitors. I have had a lot of use with an older WESTINGHOUSE "3 speed electrically reversable" window fan I acquired used 45 years ago. It sits in a window and discharges the warmer air out. it has never had any problems, except that the mechanical control thermostat no longer will switch it off when the air gets cooler.
I have given it a few drops of #30 oil over the years. A quart can lasts a long time when used for a few drops a year.

 

I ordered two new 7.5 capacitors.
Do you think the old run cap failed?
The old run cap is more than 15 yrs old. Maybe even 20. I pulled it out of an old gas furnace I bought long time ago which I never used just to get this replacement motor for the fan to run.

Did you replace the caps?
Are they motor run rated, and not of Chinese origin?
If thermally protected, it should not try to turn at all or hum , when powered, with the thermal trip operated.
If you spin it by hand and apply power, does it spin?

 

It definitely runs if I turn by hand, but the on switch is 20 feet away.
so, I turned it on, and it was humming, I crawled over to fan and spun it hard, and it ran.

Somewhere I have a capacitance meter and can't find the thing.

 

Does it run the opposite direction if spun this same way , by any chance?

 

Did not try it.
But GE motor label has an arrow with rotation direction

 

That is only if the cap is is OK , if open, a cap start/run motor is capable of either dir if spun at power up.

 

New cap, motor runs fine.
Happy to see that.

I bought 2 to have a backup. I read these caps are failing more so than they used to.

 

back to not working.
It just hums when it tries to start
I will have to take it down and take it all apart and think about what is going on with it.

Is there more than one thermal protection breaker in this motor?

Are these GE furnace, air handler blower fan motors not rated to run in attic temps?

 

The built-in Thermal-Protector may get weak after repeated overheating episodes.
I would replace the whole Fan,
it's probably cheaper to buy a new complete Fan than to buy a replacement Motor alone.
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I have found the N.A. or non Chinese versions start caps to last many years.
Try giving it a spin when applying power and see if it runs,
If it does, try a spin in both directions at start, and see if it favors just one dir.
If there were any other thermal device it should cut power completely.

 

Ok. I spin backwards. Turn on power it stops and slightly spins other way then quits. I spin correct rotation. Turn on power. Motor powers on and continuously runs so far. I turned thermostat so it will never turn off. Doing this to see if it stays running all day in hot attic.

 

Could fan bearings drag too much to start? Is capacitor wires broken? Can you measure volts on cap wires?

 

Still running. Bearings dont have play. If bearings are loose could magnetic field unevenly pull on rotor? Preventing starting?

 

Bearings can definitely cause a problem on motors such as these.
A current meter would be best to check start cap.

 

Tried holding second 7.5 cap on terminals of existing 7.5 cap and half the time it started. Tried a new supco 5mfd and would not start.
With 2 7.5, sometimes would spin half turn, quit and hum.

 

Bearings can definitely cause a problem on motors such as these.
A current meter would be best to check start cap.

Put hand on motor and it's hot. Can keep hand on it.

 

When it's hot, harder to spin start. Takes more force.

 

Beginning to suspect shorted turn{s} in motor windings.