# Squirrel cage furnace motor



## MDShunk (Jan 7, 2007)

More often than not, bad fan center relay or bad control device (thermostat).

If it's one of the newer GE ECM motors, there's a hundred more things it could be.


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## drsparky (Nov 13, 2008)

The capacitor is for starting only.


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## splinetto (Aug 29, 2008)

MDShunk said:


> More often than not, bad fan center relay or bad control device (thermostat).
> 
> If it's one of the newer GE ECM motors, there's a hundred more things it could be.


 Not new at all.....However I did install a new T stat a year ago....The problem is it runs ok for a day or two and then itll shut down..........So if I install a new or jumper the t stat I wont know if it fixed it .........I did notice the fan itself was hard to spin when it shuts down.....Would that point to the bearings......I really need to take a class...


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## MDShunk (Jan 7, 2007)

splinetto said:


> Not new at all.....However I did install a new T stat a year ago....The problem is it runs ok for a day or two and then itll shut down..........So if I install a new or jumper the t stat I wont know if it fixed it .........I did notice the fan itself was hard to spin when it shuts down.....Would that point to the bearings......I really need to take a class...


Hey man, these furnace blower motors are about 30 bucks at the supply house. If it's got tight spots, replace it on spec. Tight spots is a good enough reason to replace a motor, even if it's not a motor problem causing the shutdown. You really need to be there to see if there's power on "G" and if the motor is getting power when it's not running (and it should be). Without being there, replacing an otherwise cheap motor that presently has tight spots is a perfectly reasonable thing to do. Always, always, always replace the cap when you're replacing any cap start motor.


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## splinetto (Aug 29, 2008)

Thanks Marc


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## user4818 (Jan 15, 2009)

I wanna be like Marc when I grow up.


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## lectricboy (Mar 11, 2009)

drsparky said:


> The capacitor is for starting only.


 
Some single phase motors have a start capacitor and a run capacitor.


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## MechanicalDVR (Dec 29, 2007)

Check the amp dram on the motor with the fan compartment closed. See if the airfilter is clean if that the motor isn't getting enough air over the windings to cool it.
You coulod check the amp draw on the fan center relay but that isn't the place I would start here.


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## MechanicalDVR (Dec 29, 2007)

MDShunk said:


> Hey man, these furnace blower motors are about 30 bucks at the supply house. If it's got tight spots, replace it on spec. Tight spots is a good enough reason to replace a motor, even if it's not a motor problem causing the shutdown. You really need to be there to see if there's power on "G" and if the motor is getting power when it's not running (and it should be). Without being there, replacing an otherwise cheap motor that presently has tight spots is a perfectly reasonable thing to do. Always, always, always replace the cap when you're replacing any cap start motor.


 
True some of the basic motors are only @$30 there are some that maybe closer to $200, it depends on a few factors, I'd hate to be wrong on the higher end ones. Call backs can ruin a great rep in no time flat.


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## KayJay (Jan 20, 2008)

Damn… I’d like to know where your getting two-speed NEMA 42Y & 48Y blower motors for $30.00, because I want to start shopping there! :thumbup:
Even the MasterFit ones start at around $80.00 here, and that doesn’t even include the mounting ring or cap.


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## MDShunk (Jan 7, 2007)

KayJay said:


> Damn… I’d like to know where your getting two-speed NEMA 42Y & 48Y blower motors for $30.00, because I want to start shopping there! :thumbup:
> Even the MasterFit ones start at around $80.00 here, and that doesn’t even include the mounting ring or cap.


APR Supply. Don't know if you have them in your area or not, but they are a chain.


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## cmec (Feb 11, 2008)

LOOK at the fan and limit controll, especally if it has push in connections pull and push on them and look for discoloration.


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## KayJay (Jan 20, 2008)

MDShunk said:


> APR Supply. Don't know if you have them in your area or not, but they are a chain.


Thanks for the link. Seems they have 22 branches, which is substantial, but all in the PA area. Looks like they do offer online ordering though, so even with freight, they may still be cheaper than suppliers in this area.


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## jwiehagen76 (Jan 5, 2009)

Most residential furnaces utilize a psc motor or permanent split capacitor. The capacitor stays in the circuit. the cap is in series with the start winding. you may have a bad cap or a bearing the heats up and mtr drops out on internal ol


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## Toronto Sparky (Apr 12, 2009)

Thermally protected motors have a thermal cutout switch inside that kills the power on overheat , once it cools it restarts.


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## MDShunk (Jan 7, 2007)

Toronto Sparky said:


> Thermally protected motors have a thermal cutout switch inside that kills the power on overheat , once it cools it restarts.


That's what makes me feel pretty good about replacing the motor as the fix, since he says it has tight spots when you spin it by hand.


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## iamatt (Aug 21, 2009)

splinetto said:


> Im not up on motor troubleshooting....Hence the question...What would cause the blower to cut out in the middle of a cycle....Bad capaitor?....


Before I get blown out of the water. I did not see the other posts...
Good advise guys.

Thermostat is not usually the answer.
When you are there at the furnace check your voltage in and out from the circuit board.
If this unit is failing all the time you should be able to see voltage drop from the board to the motor.
If that is the case you know what is wrong.
Cap tester will tell you if that needs replaced.
Baring that check the amperage from the blower motor. See if it is over drawing.
The motor could be going off on thermal protection.


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## Richard Rowe (May 25, 2009)

I would run the blower motor for 30 min then check the bearings to see if they are hot and while your doing that have a meter checking the amps. If the bearings are bad then you should be able to tell after 30 min. Just be sure it is like normal operation, all panels on no extra ventalation. If it quits you will be able to find it.


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## lemau (Aug 29, 2010)

hi...i had made a basic fault finding for induction motor listed..feel free to check it..hope it can help


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