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  1. #1

    heatcraft let040bj not switching off

    The walkin cooler is freezeing things. The thermostat (White/Rogers 1609-101) was not switching at all and so replaced with new one which open and closes contact (i.e. switches) at correct temperatures but unit still runs continously. Where can I get wiring diagram/ schematic to troubleshoot further?

    Thanks
    Doug

  2. #2
    Join Date
    Sep 2007
    Location
    NH
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    1,148
    Call a pro

  3. #3
    Join Date
    Apr 2003
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    Maple Grove, MN
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    1,279
    There should be a basic generic diagram on one of the covers on the condensing unit and another one on one of the evaporator covers. Those will just get you started, though. There is also field wiring that the electrician and/or the installer had to do which might not be reflected on a diagram. There are usually a few different ways in which they can be hooked up, and from here we have no way of knowing how it was wired. As Dchappa said, it would probably be very easy to figure out for someone that knows what they are doing, and I would recommend following his advice by calling a licensed refrigeration tech.

    Good luck.

  4. #4
    Join Date
    Jul 2010
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    So-Cal
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    579
    What is the thermostat turning off when it reaches temp? Is this a pump down system?

  5. #5
    Quote Originally Posted by ammoniadog View Post
    There should be a basic generic diagram on one of the covers on the condensing unit and another one on one of the evaporator covers. Those will just get you started, though. There is also field wiring that the electrician and/or the installer had to do which might not be reflected on a diagram. There are usually a few different ways in which they can be hooked up, and from here we have no way of knowing how it was wired. As Dchappa said, it would probably be very easy to figure out for someone that knows what they are doing, and I would recommend following his advice by calling a licensed refrigeration tech.

    Good luck.
    Understand. This is the first walk-in cooler I've worked on so not familar with "typical" control approaches. But I have a Masters deg in Electrical Engineering and can figure out most anything. Was hoping someone might have a link to some technical info on the indoor evaporator unit which would make my job easier. Without that I'll have to open it up and start tracing wires until I find the switch/contactor thats stuck/defective.

  6. #6
    Join Date
    Feb 2006
    Location
    USA
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    4,381
    Quote Originally Posted by dcara View Post
    But I have a Masters deg in Electrical Engineering and can figure out most anything.

    Was hoping someone might have a link to some technical info on the indoor evaporator unit which would make my job easier. Without that I'll have to open it up and start tracing wires until I find the switch/contactor thats stuck/defective.
    So you now have a challenge ahead of you. Good luck!


    Sent from my SGH-T999 using Tapatalk 2

  7. #7
    Join Date
    Aug 2002
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    Southold.calm
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    5,616

  8. #8
    Join Date
    Sep 2007
    Location
    NH
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    Going to need an EPA license too....

  9. #9
    Join Date
    Mar 2013
    Location
    swan valley idaho
    Posts
    727
    stat likley controls a liquid line solenoid valve, which will close, causing pressure to drop, then low pressure control will open, then compressor will stop.

    clock powered by breaker-stat powered by clock- llsv closes-system pressure drops and compressor stops. ultimately lp control controls compressor start/stop

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