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Thread: 1075rpm 1/2hp condenser fan motor bad

  1. #1
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    1075rpm 1/2hp condenser fan motor bad

    On a recent call, i found the condenser fan motor bad. I have seen motors do this before but not known why. When off, the motor spins freely. When power is applied the motor locks tight and does not spin. The motor is not too expensive and has been replaced. I would like to know how and why this happens...

  2. #2
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    Who's the manufacture of the motor?

  3. #3
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    Thread Starter
    this one was by 1 Source
    but as i say i have seen it before and i believe it was OE

  4. #4
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    Bad bearings, magnetic field locks it up when power is applied by pulling it into the windings.

  5. #5
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    Did you ohm out the windings by chance?

  6. #6
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    the real question might be what made it fail. was it over charged too much heat was the wrong capacitor used. was it the right Hp rating. voltage drop?

  7. #7
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    What is the cause of bad bearings? Purely mechanical failure, maybe the fan was not balanced? Or maybe the OP just had a bad capacitor?

    Bearing Failure
    My Blower motor Hums, Spins free but won't run?

    Bearing Failure
    One of the most common problems in furnace blowers and light duty motors that use an all angle sleeve bearing is that as that bearing wears and becomes looser the magnetic field that makes the rotor assembly go around is able more easily to pull that rotor assembly against the stationary iron preventing it from rotating while power is applied. The easiest way to determine if this is the issue is to firmly grab the motor shaft while holding the motor against a bench or allowing the mounting to hold it, and see if there is movement side to side or up and down against the side of the bearings. NOTE: it is normal for the shaft of these motors to have end play- that is to be able to push the shaft in toward the motor or pull it out slightly, however there should be no play side to side. One other possibility for the failure of these motors to run, while humming, is a bad motor run capacitor. If there is an externally mounted capacitor on this motor, you can easily remmove it & bring it in we will be glad to test it for you.
    http://www.enyartelectric.com/index....&id=2&Itemid=8

  8. #8
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    Thread Starter
    The run cap checked good.
    The when no power was applied the blade spun smooth as butter on a hot skillet
    could be a imbalance issue but the fan appears to be undamaged, i know this does not mean one of the weights are all present but it sounds well while running.
    as far as ohm windings, i had no reason to, because i knew it was bad anyhow.
    ill check it later when i get off. its in the back of the truck still. Let ya know.
    Voltage was not out of balance

  9. #9
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    No big deal, motors will fail, maybe the OE was made in China or just old? It is nothing to over analyze, I just put some anti seize on the shaft for next time so the blade comes off easy.

  10. #10
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    yess indeed!
    changing the same part repeatdly on the same equipment is a great way to keep the pocket fat but does not keep the business name shiny.
    matter of fact this motor came with a one year warranty and we changed it 14 months ago.
    personally i am somewhat embarassed.
    I pride myself in what i do and if my repairs dont last i feel it has something to do with install error.
    Not necessarily, i kno, but i still would like to learn from my mistakes and not make money off them.
    Thank you for your opnion Mr. Eugene.

  11. #11
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    14 months ago, was it made it China? If so it tell your customer, hopefully they understand?

    I got over the fact that parts being supplied went to crap about 10 years ago, and the trend is getting worse on bigger items, it is not your fault or mine. Blame the corporations with the politicians in their pockets. Hopefully the politicians and CEOs have multiple failures on their durable goods, and I hope they get uncomfortable while waiting for the repeat failures due to crappy imported parts.

  12. #12
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    Funny guy!!!!
    ill keep that in mind next time im on a call 7:30 on a friday!!!!

  13. #13
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    Quote Originally Posted by 02JeepKing View Post
    yess indeed!
    changing the same part repeatdly on the same equipment is a great way to keep the pocket fat but does not keep the business name shiny.
    matter of fact this motor came with a one year warranty and we changed it 14 months ago.
    personally i am somewhat embarassed.
    I pride myself in what i do and if my repairs dont last i feel it has something to do with install error.
    Not necessarily, i kno, but i still would like to learn from my mistakes and not make money off them.
    Thank you for your opnion Mr. Eugene.
    One's pocket will not stay fat long if the business name becomes tarnished...

    Probably a different wording of a Proverb or Chinese saying.
    GA-HVAC-Tech

    Your comfort, Your way, Everyday!

    GA's basic rules of home heating and AC upgrades:
    *Installation is more important than the brand of equipment
    *The duct system keeps the house comfortable; the equipment only heats and cools (and dehumidifies)
    *The value of comfort, over the long term; leave economic choices behind!
    Choose your contractor wisely!

  14. #14
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    Thread Starter
    Source 1...
    I think Germany?

  15. #15
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    must not have caught the idea Mr. Ga hvac tech
    re-read what you highlighted.
    can you spell sarkastick?

  16. #16
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    Quote Originally Posted by 02JeepKing View Post
    must not have caught the idea Mr. Ga hvac tech
    re-read what you highlighted.
    can you spell sarkastick?
    Spelling is not my forte.. My posts would be horrible if computers did not clean things up for me.

    Agree with the thought...
    GA-HVAC-Tech

    Your comfort, Your way, Everyday!

    GA's basic rules of home heating and AC upgrades:
    *Installation is more important than the brand of equipment
    *The duct system keeps the house comfortable; the equipment only heats and cools (and dehumidifies)
    *The value of comfort, over the long term; leave economic choices behind!
    Choose your contractor wisely!

  17. #17
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    Thread Starter
    back on topic i do believe the bearing theory was correct.
    i dug the motor out the scrap bin today and the shaft did have a small bit of play paralell.
    i know the shaft normally moves up and down slightly but this one had an odd movement left and right. although slight possibly this was the culprit.
    too bad they cant make motors as well as they cook huh Mr. Eugene?

  18. #18
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    Yeah, it is usually bearing failure, cap failure usually will not lock it up.

  19. #19
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    was it one of those multi horse motors? I find those only last about a year because getting the right amp draw from the right speed and capacitor combination can be difficult.

    Sent from my XT901 using Tapatalk 4

  20. #20
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    An old thread resurrected, but nobody ever actually answered your question.

    When a motor starts the magnetic field induced in the stator tries to pull the rotor to one side, but it can't so it turns, then as the current reverses the rotor continues on chasing its tail. When you get enough lateral play in the bearings (side to side) that rotor is actually pulled into the stator when energized and you end up with a very expensive drum brake. If you were able to manually get that motor spinning fast enough and then energized it the magnetic field would likely hold it centered and it would run.

    What causes the bearing failure? Sometimes it could be a fan out of balance, but often anymore it seems to be shotty construction and cheap materials. How often have we all seen a shaft-down motor that is nothing but an oil slick between the motor and the fan blade, and often less than a year old?

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