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  1. #1
    Join Date
    Jul 2011
    Posts
    14

    Compressor icing question

    Hi I have a question about a system I am looking at.
    It's a dual evaporator walk in cooler running 404a.
    It has low head pressure, high suction pressure, very low superheat on both evaporators, and the whole compressor is icing up. Al so the sight glass has fast moving bubbles pretty much constantly.

    My guess is that the installer used the wrong size orfices or TXV (too large) and it's flooding back.
    Any input would be appreciated.

  2. #2
    Join Date
    Sep 2007
    Location
    NH
    Posts
    1,109
    Are you not able to check the TXVs or evap coils... Maybe the bulbs aren't tight or even hooked up.

    I would just go take a look and get the info of the valves and compressor.

    Some actual pressures would be nice to. And SH.
    Sounds like its flooding but tuff to tell with limited info.

  3. #3
    Join Date
    Jul 2011
    Posts
    14
    head pressure +-160psi suction +-76psi superheat 1-2 degrees on both evaporators(taken separately at port inside evap coils). The bulbs are mounted and insulated. The system has a HPR valve. I did pull the fan lead to see what would happen and the head pressure started to climb but the compressor stared to make some very odd noises like it wasn't happy at all.

  4. #4
    Join Date
    Jan 2009
    Location
    Salisbury, Maryland
    Posts
    123
    How old is this system, it every worked right? I see you finally got some pressure's posted, what about the OD ambient when taking readings? Double check your subcooling and superheat, 404a is a blend so get your bubble and dew points correct. If you really do have 1-2 superheat, that compressor is indeed upset and is probably contributing to a lower than normal head pressure too due to flooding.

  5. #5
    Join Date
    Feb 2008
    Location
    California
    Posts
    2,057
    Here's the deal.

    Your expansion valves are overfeeding.

    Figure out why.

  6. #6
    Join Date
    Jul 2011
    Posts
    14
    Quote Originally Posted by Phase Loss View Post
    Here's the deal.

    Your expansion valves are overfeeding.

    Figure out why.

    Like I said my guess is the installer used orifices that were too large. I am not sure if it has ever run right as I only just got this contract and have only done a preliminary inspection off all their equip. I will have to get the OK to go ahead with more work and will pump it down and pull a powerhead off and see what cartridge is in the valves. The box is running proper temp and the ambient was about 60F BTW. But seeing the whole suction line and compressor shell completely covered with ice and bubbles in the sight glass I knew that compressor won't last long.
    ALSO the owner told me after the equipment was moved from the other location it was in originally he has lost at least 6 YES 6 compressors so I know whoever he was using really didn't know what they were doing.

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