Replace Exhaust Fan Motor in free-standing AC unit?


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Old 05-12-13, 05:01 PM
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Replace Exhaust Fan Motor in free-standing AC unit?

I have an old free-standing AC unit, the kind that vents with dryer hose (model Maytag NMPEB08F2A*B serial AR761121 021W) that is not cooling. I hear the compressor kick on for a few seconds or minutes, but the air that comes out the front isn't cold, there is no air, hot or otherwise, coming out the exhaust vent, and the compressor shortly kicks off. If I stick my hand into the vent (where the dryer hose attaches) I can feel a drum that rotates if I flick it, but doesn't spin on its own when the unit is turned on. I stuck the intake of an air mattress pump into the vent, which did pull very hot air out of the unit, and also allowed the compressor to stay on and blow cold air. So, I think I have some problem with the exhaust fan, or whatever blows the hot air out the exhaust vent, that is causing the unit to overheat and kick off the compressor. I took the plastic cover off the unit, but otherwise I don't know how to take it apart. Any help much appreciated.

Jess
 
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Old 05-12-13, 05:22 PM
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Welcome to the forums.

You'll need to be a true DIY'er to work on that unit. I was looking at the available parts for that unit and they are in short supply. It looks like the fan motor may be available for around 80.00

If the fan/blower spins freely by hand it may just need a new capacitor. Unfortunately it would need to be matched by actually reading it off the unit. If the fan/blower is binding you may try oiling it where the shafts enter the motor.

I could not find any online manuals for that unit. You'll have to search and locate all the screws holding it together. I can't be of much help without actually seeing the unit.
 
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Old 05-12-13, 08:47 PM
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Re:

Thanks for your reply. Can you explain to me how the hot air gets out of an air conditioner? Is the fan that propels hot air out separate from the fan that blows cool air into the room? Air is blowing out the front, and the front fan responds when you change the fan speed. I am not all that handy, but since it probably won't end up being cost effective to fix it anyway, I don't mind risking it. If I do figure out what's wrong and can find a part number, but changing it out is over my head, I could order the part and call someone. I might not bother calling anyone if I don't have a more specific idea what's wrong, though.

Pictures/video
https://plus.google.com/103147864418351203579/posts
 
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Old 05-13-13, 12:10 AM
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With most air conditioners there is one motor with two shafts. There is a fan on one end for the outside duties and a blower on the other end for the inside air.

In the parts link I left below it shows two separate motors. That would mean that in your case the outside fan or the condensor fan would be changed by itself. This would be the fan that pushes the hot air out the duct.

Appliance factory parts maytag - nmpeb08f2a
 
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Old 05-14-13, 12:41 PM
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Re:

Thanks again. I think I'll start unscrewing some screws and see if I can find something that looks like the condenser motor you linked to.
 
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Old 05-16-13, 04:29 PM
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Re: capacitor

We were able to get the capacitor off. The specs say 6 mF, 250 V, 50/60 Hz.

I'm attempting to attach a photo. If that doesn't work, it's also at the Google+ link from above. I didn't have much luck searching for the numbers I read off the capacitor on Google or eBay. Are these types of capacitors specific to air conditioners? Are the 450V ones which seem to be more common ok to substitute? Is the capacitance important?

Thanks again,
Jess
 
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Old 05-16-13, 05:32 PM
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Capacitors from eBay

Are either of these compatible? They look a little different, but the specs look right.

Ceiling Fan Capacitor 1 6 MFD 6 uf 250V 2 Universal Terminal 50 60Hz | eBay

Ceiling Fan Capacitor CBB61 5uF 6uF 4wire 250V | eBay

Thanks again,
Jess
 
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Old 05-16-13, 06:20 PM
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Thumbs up

Every brand is slightly different

The first one..... 6 mfd@250 is perfect. Almost an identical replacement.

Feel free to use a 6 mfd @ over 250 vac. It only needs to be at least 250 vac....it can be over.
 
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Old 05-17-13, 03:29 PM
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Re: new capacitor

Great, thanks. I ordered the almost identical capacitor, and it should get here some time next week. Does it matter which terminal the blue and white wires get hooked to? I can tell the terminals apart on the old capacitor because one is connected to that extra prong, but from the picture it looks like that extra prong is in the middle on the new one.
 
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Old 05-17-13, 09:06 PM
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The polarity doesn't make a difference with an AC capacitor.
You can connect them in either direction.
 
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Old 05-22-13, 08:52 PM
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Re:

I'm updating, unfortunately not with good news. I hooked up the capacitor, but the condenser motor is still not moving. If I stick my hand up the exhaust and flick the blower wheel, the middle of the motor spins and vice versa, and there is no catching or binding, the compressor just runs for awhile and then overheats, shuts off, and starts blowing hot air into the room with no movement from the condenser motor. I'm pretty sure the new capacitor is good because it threw a spark when I disconnected it. I can't figure out how to get the motor off, or the metal plate behind it, so I think it's probably at the point of tossing the unit unless I want to stick some sort of external pump in the exhaust hose, which probably wouldn't be terribly safe or effective. But wanted to come by and say thanks for the quick and helpful responses.

Jess
 
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Old 05-22-13, 08:58 PM
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Unfortunately those units were not designed for service and can be a problem to disassemble and work on.

You gave it a good try.
 
 

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