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  1. #1
    Join Date
    May 2008
    Location
    NJ
    Posts
    23

    Randell Display Case Question

    Unit M#4149SCAM , S#W0000005354 , R-134A. Complained of high temp in the case. Check the condenser coil and it is clean. Compressor is running but really hot and shutting off on overload. Check the evap coil and found 3/4 of it is solid ice. I defrosted it and found the bulb for the pressure control,zip tied on the surface of the evap coil and txv not insulated. I place it back inside the middle of the coil and insulate the txv. I did the right thing...right? Now I am not sure. When I turn the unit on, the compressor only runs for about 30-45 seconds, hot and still appears to be going off on internal overload. I adjusted the pressure differential/cut-in but the compressor will only run the same. I then put my gauges and now I have equalize reading on both high and low side with the compressor running? Is this even posssible? Or I just hearing the compressor running but it is not really compressing? I did not finish the diagnostic because I have to leave due to the area is getting busy and I am in the way.
    I wanted to check for leak but with pressure equalized I told the boss that the compressor is bad(but did not have enough time really to check it). And will do the leak check when we come back for the replacement.
    Please be easy input......newbie

  2. #2
    Join Date
    Oct 2008
    Location
    Canada
    Posts
    83
    why are you looking for a leak? Make certain it's the compressor before you replace it, did you check the start cap?

  3. #3
    Join Date
    Aug 2007
    Location
    Reading, Pa.
    Posts
    456
    Simple..If there is a suction service valve front seat it fully and see if the comp. pulls in a vacuum (atleast 20inch guage) if not the compressor is toast and replace it then diagnose the rest of the system. Prolly the loose bulb led to flooding the compressor and killing it.

    my 2 cents
    We the willing, led by the unknowing, for the ungratefull, have done so much for so long with so little, we are now qualified to do anything with nothing.

    Refrigeration is all the same weather your making Ice, refrigerating or freezing the product.

  4. #4
    Join Date
    Feb 2010
    Location
    Atlanta, Ga.
    Posts
    24

    loose bulb

    I need to extend this post;
    I am working on the same unit, evap. frozen. Differential bulb was just sitting in front of evap. Valve and sensing bulb seemed to be installed right.
    I know there was a butcher working on this, hot gas line was cut and not runninging thru the condensate pan and a timer was put in to shut the unit completly off at night to defrost. Customer complained of water on the floor in the morning.
    My pressures were 150 high and 7 low which is really low. No matter what I do I cant get the low up to around 20 where they belong. I'm thinking tx clogged. Would the bulb not inserted in the evap. coil make the pressure that low. I'm thinking not. What I was going to do was replace valve and filter and insert bulb in coil the proper way.
    Anyone?
    thanks
    Nick
    Last edited by lafam1; 07-24-2012 at 01:19 PM. Reason: clarification

  5. #5
    Join Date
    Jun 2007
    Location
    Williamsport, PA
    Posts
    176
    If you are talking about the bulb for the txv, it should not be insurted in the coil it should be attached to the suction line at the outlet of the evaporator.

  6. #6
    Join Date
    Feb 2010
    Location
    Atlanta, Ga.
    Posts
    24

    not tx bulb

    The tx sensing bulb was correctly installed on the suction like I said. I was talking about the bulb for the differential control that was just hanging out in front of the evap.
    Would that make my reading low, was my question.
    sorry my paragraph was not clear.
    Nick

  7. #7
    Join Date
    Jun 2007
    Location
    Williamsport, PA
    Posts
    176
    Then I am assuming that you are talking about the thermostat bulb and you are correct, that would not cause your pressures to be low. To determine that your txv is not working you need to have a no ice on the evaporator, proper charge and then check the superheat.

  8. #8
    Join Date
    Feb 2010
    Location
    Atlanta, Ga.
    Posts
    24

    Thanks

    Yes the thermostat Bulb.
    No matter how I adjust my charge I cannot move my low side from about 7 psi.
    High side is no problem.
    With evap. defrosted and proper charge of 40oz. My pressures were 150 high and 7 low which is really low hence the freezing evap. so I'm assuming clog in tx.
    Would my assumption be correct?
    Nick
    Last edited by lafam1; 07-24-2012 at 09:31 PM. Reason: added

  9. #9
    Join Date
    Oct 2008
    Location
    Ohio, USA
    Posts
    181
    lafam I just quickly read your posts, but it sounds as you have a restriction. Check filter drier and line set going into evap, but my bet is it's the TXV. (More specifically, the inlet screen is plugged)

  10. #10
    Join Date
    Feb 2010
    Location
    Atlanta, Ga.
    Posts
    24

    thanks

    That is exactly what I am going to do.
    Thanks to all who replied!
    Always good advise here!
    Lafam1

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