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Thread: Condenser fan running backwards

  1. #21
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    Quote Originally Posted by buttwheat View Post
    Easy pull the rotor out and reverse it
    Quote Originally Posted by Hrdworkingacguy View Post
    Give that man a cigar...

    Wonder how many people on here have run to a parts house or opened a parts house having a motor on their truck that's right except for direction and didn't realize this...It happened quite often at my last company I worked for...
    Except now your wires are going to be down by the fan blade.
    We're awl pawthetic and kweepy and can't get giwrls. That's why we fight wobots.

  2. #22
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    Quote Originally Posted by chaard View Post
    Except now your wires are going to be down by the fan blade.
    I didn't say it would be perfect I just answered the question
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  3. #23
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    Thread Starter
    So strange, I had another one today, anyone else seeing this?
    http://youtu.be/HI8ldPaGGA0
    There are two ways to do things, Right and Again.

  4. #24
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    Had a condensor fan motor once would run backwards w/ new dual cap on it. did separate caps of same rating, ran normal.
    Col 3:23


    questions asked, answers received, ignorance abated

  5. #25
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    I found one a couple years ago on a 20 something year old unit. When I got there, coil was frozen but fan was blowing backwards on outdoor. Verified wiring and checked cap, all was good. Shut it down and came back the next day with a new motor and cap(it was after hours and temperatures weren't that bad anyways). When I Came back the lady's husband had flipped the disconnect, he said it ran fine all night. Turned it back on and sure enough it ran the right way. Repeated the test multiple times and it wouldn't rotate backwards again. Explained to her husband I know it was backwards yesterday but there's no way I can prove it to you now. My recommendation was to go ahead and change it but he took the option to just check it out and clean it up, so I did. Less than a month later I was back, motor was making a ruckus, hot as could be and spinning backwards again. Needless to say, new motor. He thought it would only cost $x (the difference in the two quotes the last trip) and after some discussion back and forth he finally caved and agreed to pay the second service charge si was picking up the motor and cap and getting ready to walk back to my truck. Told me it wasn't fair, but listening to his wife when she got home and the ac wasn't fixed would be even more unfair. I don't give the option any more, problems seldom fix themselves when electricity is involved. New motor and ALWAYS new cap.

  6. #26
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    Also found one spinning very slow backwards when unit was off. Touched to unit and got zapped. Turned off breaker and found ground rubbed through one lead wire feeding something like 76 volts through unit. No ground coming into disconnect. Fixed wire, ran ground to main house ground wire 2' away and checked cap and compressor just to be safe before turning it back on. Still running as far as I know.

  7. #27
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    Thread Starter
    The second one yesterday, I found it running backwards on new cap I had just installed two weeks ago during startup, pulled disconnect, got homeowner husband (H/O wife walk outside with me) installed disco and it spins clockwise(correct) again, pulled disco again and it spun backwards again. I replaced motor today when I got there it was spinning backwards and satisfied stat when I was looking at it, went inside turned stat down and it spun correctly again. The reversible wires some previous hack had wired in above fan guard were brittle from sun, maybe somehow they were touching.... I just don't know.
    There are two ways to do things, Right and Again.

  8. #28
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    Isn't it fun when everything works prefect when you're trying to show a customer your findings? it's even more fun when you're trying to find a dead spot in the windings after you broke it free. I don't break it free until the customer has seen it sitting there humming first.

    I always describe it to them like going to the Dr office. By the time you get in you feel better.

  9. #29
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    Depends? Time of day ,how far out. Did I use my universal already.

  10. #30
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    Quote Originally Posted by 71CHOPS View Post
    its wired wrong. motor line and common is wrong at the cap.
    Registered to say this was my issue. Took pic before replacing cap, couldn't tell where fan went due to bad angle on picture. Fan was running backwards so I switched the fan wire between common and fan, fixed the issue.

  11. #31
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    The air conditioner at my grandparents house blew air in the wrong direction for close to 30 years, and never missed a beat. It was a Signature Series from Montgomery Wards, not sure who made those. I deduced that sometime shortly after it was installed in the early 70's, that the fan was replaced incorrectly. Killed all the grass in a wide circle around it. This was when I was growing up, I thought it was odd, but never questioned it.

    When my grandfather passed away, I moved in there and used that ac for almost another ten years and later replaced it, but it was still running fine.


  12. #32
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    I think you got a bad motor.

  13. #33
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    The next time I see, or create, a job with a reversible condenser fan motor - I am going record a full set of performance numbers. Then I am going to reverse the fan direction and re-record all the numbers.

    Although, for the comparison to be strictly fair; the fan blade would have to be changed as well.

    A while ago at a no-cool call I replaced a condenser fan motor on a horizontal-air-flow residential condensing unit. There was a fan shroud and the original rotation had been blow-through. This arrangement tends to perform less well as the fan tends to 'blow a hole' through the coil. This is because the fan blade creates a circular high pressure area ahead of itself - leaving the remainder of the rectangular coil with less, and sometime no, air flow - especially the corners of the coil.

    Whereas a pull-through fan creates a low pressure area across the entire downstream side of the coil - with the result that the airflow through the coil is uniform across the entire entering air side of the coil - because the entering air pressure is exactly the same.

    So I changed the rotation on that call to provide pull-through air flow. Later that day the customer called to say that I had done something wrong and he wanted it corrected. I stopped by and explained that my work provided an increase in performance and efficiency for him. I reversed the rotation and showed him that the head pressure was lower using pull-through.

    "But it's been the other way for 20 years."

    "Say you were spelling a word wrong for 20 years and then learned the correct spelling - would you continue to spell it wrong?"

    And I made him a sketch, and detailed why I had done it - and I left it with him. A few days later he called to say that had called his engineer-friend - who said that what I had done was the correct way. The customer still said that he didn't like it.

    "But it's better all around for you."

    "But it was the other way for all these years . . . . and we never had any problem with it . . . "

    "Are you having a problem with it now?"

    No . . . but we might . . . "

    After about another week he called back to say more of the same. Later than day I stopped by and changed the rotation back to the original direction. <g>

    https://www.youtube.com/watch?v=452XjnaHr1A

    I routinely hear the words in the above video (from 0:20 to 0:32) ringing in my ears.

    PHM
    ------------



    Quote Originally Posted by CHAINIK View Post
    The air conditioner at my grandparents house blew air in the wrong direction for close to 30 years, and never missed a beat. It was a Signature Series from Montgomery Wards, not sure who made those. I deduced that sometime shortly after it was installed in the early 70's, that the fan was replaced incorrectly. Killed all the grass in a wide circle around it. This was when I was growing up, I thought it was odd, but never questioned it.

    When my grandfather passed away, I moved in there and used that ac for almost another ten years and later replaced it, but it was still running fine.
    PHM
    --------
    Socialism is a zombie. It never dies - even though it is constantly decaying and decomposing.

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  15. #34
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    Was it one of those slab condensers that look like large mini splits? I know Carrier and ICP have similar models.
    I cant figure their logic behind that blow through fan. It works fine, but its weird, it confuses the installers and seems like it would work better the other way.

  16. #35
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    No; it was an old rectangular Heil unit. Lennox used to make the twin to it.

    PHM
    -------


    Quote Originally Posted by CHAINIK View Post
    Was it one of those slab condensers that look like large mini splits? I know Carrier and ICP have similar models.
    I cant figure their logic behind that blow through fan. It works fine, but its weird, it confuses the installers and seems like it would work better the other way.
    PHM
    --------
    Socialism is a zombie. It never dies - even though it is constantly decaying and decomposing.

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