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  1. #1
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    condenser fans not running on walk-in freezer

    I apologize if this is not the right section of the site to post this and that its not in the pro forums but regardless, if you guys could help me with this that would be great. I have a walkin freezer with two condenser fans one on a thermostat both not running. There is power to both, the run capacitors are fine by capacitance check, bearings spin freely, the motors are cold to the touch and the windings have measurable resistance. Any ideas?

  2. #2
    Joe Harper's Avatar
    Joe Harper is offline AOP Committee/Professional Member*
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    Thermostat faulty

  3. #3
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    thermostat

    Only one is operated by thermostat. And besides, there's proper voltage at the motors. the manager said it stopped working when it started raining two days ago. Its still raining now, but I have a cover over the unit now.

  4. #4
    Joe Harper's Avatar
    Joe Harper is offline AOP Committee/Professional Member*
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    You can have voltage, but no current flow. Did you check the points on the contactor?
    Is this a single or 3 phase unit?

  5. #5
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    When you say you have power to both fans, where are you measuring the voltage, between live (hot) and neutral or live (hot) and earth (ground)? And you say that you've checked the run capacitors... what about the start capicitors?

    If you have voltage between the live (hot) and neutral terms and the start capacitors and windings are sound, then the motors should run. The only other thing that could stop them from starting is the centrifugal switch could be jammed open or its contacts badly worn, if its an older type motor. But if this was the case the run windings would get hot but you say that the frame is cool.

    Are you sure that your checking you have voltage in the right place? I had a customer who said the same thing. And it turned out he was using a volt stick, and couldn't understand that they only measure dense flux adjacent to a live conductor. It turned out there was a loose neutral in the terms box.
    Martyn

    50 & 60 hz but 100's worse

  6. #6
    Joe Harper's Avatar
    Joe Harper is offline AOP Committee/Professional Member*
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    Fan motor chilly

    Is this a mac 8 or mac 9 unit on top of a McDonalds??

  7. #7
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    Quote Originally Posted by Joe Harper View Post
    You can have voltage, but no current flow. Did you check the points on the contactor?
    Is this a single or 3 phase unit?
    If the windings are not open or grounded, how could you have voltage with no current flow? Is this a bad path to ground(nuetral) type of problem?

  8. #8
    Joe Harper's Avatar
    Joe Harper is offline AOP Committee/Professional Member*
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    You dont have enough conductor to carry the flow required to spin the motor, but enough to get a voltage reading. Many a tech has cursed at a contactor that they got a voltage reading off of only to find this out.

  9. #9
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    Lightbulb

    Quote Originally Posted by Joe Harper View Post
    You can have voltage, but no current flow. Did you check the points on the contactor?
    Is this a single or 3 phase unit?
    Say it ain't so Joe!

  10. #10
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    Are you talking about the fans inside the box or outside the box? If they are the ones inside the box, then the following may be of help.... The walkin freezer at my last job had 2 fans inside the box. They were always "hot." However, on the coil on the inside of the box, there was a small thermostat, bout 3/4" in diameter and about a 1/2" thick. The thermostat switched the neutral. If the coil temp was warm, the thermo would open the neutral circuit and shut the fans down. The interior fans may not run until the interior coil gets cold to prevent the fans from blowing water into the box.

    If its the fans on the outside of the box, I would think they would switch on and off with the compressor. Check the wiring, and check the windings for opens and shorts

  11. #11
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    If you are measuring the voltage at the correct points, meaning right to the motors, and tried a good capacitor for assurance, then the likely scenario is, one motor was out for a while; the manager thinks both motors were running; while one of them was actually running and the second one was just spinning from the draft; when the second motor failed too, you got called.

    The other likely scenario is, you are not a refrigeration technician.

  12. #12
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    Is everyone on the same page on the location of "condenser fans"?

  13. #13
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    Quote Originally Posted by smilies View Post
    Is everyone on the same page on the location of "condenser fans"?
    I know condenser as being outside the box, but with the mentions of thermostat controls, makes me wonder what fans the OP is actually talking about. The walkins I've dealt with have all refrigeration components accessible from outside the box, including all the fans...

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