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

Will that show on an ohm meter? The yellow to white is around 3.5 ohms on this 4 speed motor. I could switch wires for different speed. Would that fix a shorted winding , like associated with speeds?

 

Motor acts like last 3 hvac condenser motors that failed on me over last 20 years. Humm no start. Checking never could find anything wrong. New cap no start. New motor good to go. Seriously, those motors seemed good. Bearings good, just mysterious to me.

 

One furnace blower motor run for several years with additional caps tied in parallel with the original cap that id not start it after the first heating season. That was probably an added total of 2 or 3 mfd.
There is a check for shorted turns but I don't know what it would be.
Probably just a few shorted turns out of a couple hundred will not show on a meter. But check for leakage to the frame, that would certainly be a serious fault that will cause problems.

 

One furnace blower motor run for several years with additional caps tied in parallel with the original cap that id not start it after the first heating season. That was probably an added total of 2 or 3 mfd.
There is a check for shorted turns but I don't know what it would be.
Probably just a few shorted turns out of a couple hundred will not show on a meter. But check for leakage to the frame, that would certainly be a serious fault that will cause problems.

Will try different speeds. If no better will tear it apart looking for something related to coils and bearings. When it hums, it's very tight feels jammed.

 

I do have another gas furnace and motor . I can try that motor if this one refuses to cooperate. It also had a 7.5 cap in it. Looks like a similar multi speed.

 

after running for an hour, motor overheated and shut down.
When it cooled enough to restart it just hums, till it overheats again enough for thermal breaker to trip off.

Next step try a different speed winding, if that no worky, take it apart and likely try the other motor.

 

Either a motor is tight and difficult to rotate or it spins freely. Tight can be either bearing friction or bearing alignment.
If it spins freely then it is none of those issues.
A capacitor motor requires a phase difference great enough to produce some torque to spin it. Poor quality capacitors may not have enough capacitance or may have excessive leakage current, or both. Or they may be open circuit or shorted circuit due to breakdown.

 

GE motor #2 has burned coils. Not a lot. IMO, dead now.

 

Motor #3 is Emmerson, bearings perfect, runs with same 7.5 cap. Multispeed.
Coils look good.
Motor has oil ports, cannot be taken apart, motor steel shell is pressed down to hold end caps.
I hope it does not burn out. Are these motors rated for attic temps?

 

Motor says INS CL A 40C
Higher temps destroy these things??

Attics do not boil water though
Motor Nameplate Letter Code Designations | Pumps & Systems (pumpsandsystems.com)

 

130 *F is 54*C
My attic never gets that hot. Reading an attic at 130 is damaging to the house.
I do also have a ridge vent and the southern early thru late afternoon roof is entirely shaded by a massive water oak tree.
I don't think my attic is too hot for these motors.

 

Having only those few turns burned indicates a short across just those turns. I suggest an examination to discover what happened for the reason of avoiding it happening again. A few turns seldom short circuit for no reason.

 

GE motor #2 has burned coils. Not a lot. IMO, dead now.

It only takes a couple of shorted turns to prevent normal operation/RPM etc.

 

Emerson motor is installed and working

 

Having only those few turns burned indicates a short across just those turns. I suggest an examination to discover what happened for the reason of avoiding it happening again. A few turns seldom short circuit for no reason.

I could see nothing wrong inside the motor to cause that.
I know that is an older motor, it has oilers. I think was in my inlaws home air handler and I replaced it as it occasionally would just not work for them. But I could never see anything wrong and I had taken it apart years ago to look. I kept it and it did run for a few days in the attic working normally. I tend to keep stuff. I just salvaged the wires as nothing wrong with them. If it was not a pain to pull the copper for recycling, might do that too. I think will keep the bearing shell ends as they have oilers. Should bolt right on a similar GE motor.

 

Hey guys, I just found an issue that might have caused the GE motor to burn out??
Capacitor cap when installed was connecting to the terminal, and the cap is grounded.
I discovered that when with just the white wire disconnected, the fan RAN!
Emerson wires too short to reach cap, so I added the GE cap wires to the Emerson cap wires.

I ohmed the white to ground and it is open, so Emmerson motor is not shorted to ground.

If the capacitor wire, one or the other is grounded what will that do to the motor windings?
Overheat them?

I left cap off. I bent down the wire lug some more. See the GE motor lugs are straight, and bent them over 90* to fit with cap on, but I guess did not bend them down enough.

You can see in pic, inside the cover it looks to have made electric contact.

 

I may swap out these ends for 90* terminals, I have a bunch somewhere.

AND, was thinking a cap cover, what happens when the cap end swells up, shorts the cap wires to ground?
The first motor had a swollen bad cap and a cover, maybe it shorted too. Who knows.

 

Been running in Attic all day. Motor is not overheating, staying cool and cooling my attic nicely.
Even when it's not broiling hot outside, having that fan running keeps the upstairs cooler and the AC does not run as much.

On this one it is on medium high speed setting.

Does anyone know how much less cost of running a motor depending on it's speed setting?

I sure learned about how bad caps and badly installed caps can destroy an electric motor. The first 2 motors were freebies, this 3rd one, yrs ago bought an entire NG furnace for $40 as a potential replacement.

 

Does anyone know how much less cost of running a motor depending on it's speed setting?
I sure learned about how bad caps and badly installed caps can destroy an electric motor. The first 2 motors were freebies, this 3rd one, yrs ago bought an entire NG furnace for $40 as a potential replacement.

Not a great deal between speeds.
Always make a point of only using caps that state "Motor Run Rated

 

The tool to use to get that information is the "Kill -a-watt" device. The best price for it was at Harbor Freight, a whole lot less than elsewhere, half the price at Home Depot.