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  1. #14
    Join Date
    Apr 2011
    Location
    Klein, Texas
    Posts
    11
    Quote Originally Posted by Dallas Duster View Post
    So all 3 are sweating?
    No just the bottom ones are sweating.

  2. #15
    Join Date
    Oct 2011
    Location
    South Georgia
    Posts
    68
    Try removing 5 # of the refrig charge and see what happens.

  3. #16
    Join Date
    Apr 2011
    Location
    Klein, Texas
    Posts
    11
    I shorted the charge at first the result was slightly different and it ran okay until the last compressor came on. It shot right up from 450ish to above 600 and a diag showed up.

  4. #17
    Join Date
    Jan 2008
    Location
    Dallas ,Texas
    Posts
    3,722
    I think you need to run as many compressors as you can to stay online and get a log of temps and pressures and subcooling.

    Edit: does the unit have a motor master?

    Quote Originally Posted by Eastcoasttech View Post
    I shorted the charge at first the result was slightly different and it ran okay until the last compressor came on. It shot right up from 450ish to above 600 and a diag showed up.

  5. #18
    Join Date
    Oct 2011
    Location
    South Georgia
    Posts
    68
    Eastcoast help me out here. Is this "restriction" symptom occuring in one coil or more than one coil in the parallel pack? That model vintage had some issues with dataplate charge on the lbs per circuit. Dallas i think you are correct, need to get stabilized and check subcooling, superheat, fan amps, etc. Incidentally i have had to remove 10 to 12 percent of nameplate to get the charge down to where the hpco wouldn't cut out

    I bought an expensive digital gauge that records and holds min/max pressures. I was amazed at the momentary spike at start up for a hot set of coils that were restarting after a short stop (cycling). 600 + psi for just a second at start up, reduced charge to calm it down and get some subcooling.

    This sounds like liquid backing up somewhere, you did say this is a three pass coil?

  6. #19
    Join Date
    Apr 2011
    Location
    Klein, Texas
    Posts
    11
    Well first I pulled 83 # of gas out. We had the coils replaced and recharged with 80 lbs because that's all we had at the time. There are four compressors and the problem is across all sets and if the coils are six feet across then two feet get warm and the remaining four stay cold. Walking on top of the unit, the right side farther away from the header is blowing cold while the header side blows warm/hot. It's almost like the refrigerant isn't making it across to the other side and only going in and out like the coil is "backwards". The display shows 11 degrees SH

  7. #20
    Join Date
    Jan 2008
    Location
    Dallas ,Texas
    Posts
    3,722
    All coils meaning the one`s your guys changed out plus the other circuit??

    Quote Originally Posted by Eastcoasttech View Post
    Well first I pulled 83 # of gas out. We had the coils replaced and recharged with 80 lbs because that's all we had at the time. There are four compressors and the problem is across all sets and if the coils are six feet across then two feet get warm and the remaining four stay cold. Walking on top of the unit, the right side farther away from the header is blowing cold while the header side blows warm/hot. It's almost like the refrigerant isn't making it across to the other side and only going in and out like the coil is "backwards". The display shows 11 degrees SH
    UA 100

    It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.

  8. #21
    Join Date
    Apr 2011
    Location
    Klein, Texas
    Posts
    11
    The circuit in question is the only circuit on this machine that has issues. Circuit A. B circuit hasn't had a chance to run as yet. But I'm sure it will as well. There are three machines at this facility but only one required the coil change out.

  9. #22
    Join Date
    Aug 2002
    Location
    Greenville SC
    Posts
    434
    Don't know why your coil would be sweaten, but I bet you are over charged. 425 with only one compressor running is way to high. You can over charge very easily with a Micro Coil. IF you are weighing the charge in and it calls for 86 lbs. I would only put in 82. One pound over will really jack your head up. There should be a charging procedure in the IM manual that works a lot better than weighing the charge in.

  10. #23
    Join Date
    Sep 2004
    Location
    Kansas City, Kansas, United States
    Posts
    13,833
    that is confusing???

    the bottom most suction one??

    I have several 30rb chillers and have changed many coils and hoy gas tees!


    ONE tiny tiny tiny little piece of dessicant from a dryer or a grain of sand will restrict MDX coils!!!!!!!!!!!!!!

    I have a couple 180tr 30rb 410a chillers with 8 compressors.
    they only hold about 80lbs per circuit?????????????????

    did you pull the charge and weigh it in???

    sounds to me like it is over charged?

    it only takes a couple ounces!!!!!!!!


    Quote Originally Posted by Eastcoasttech View Post
    Okay there are three points where the header attaches. Top middle and bottom. The two top most flanges are abnormally hot. The bottom most "suction" one was cold and sweating like it was a suction line. I'm going to check in the morning for that aluminum horizontal line.
    I WILL SELL WORK,GENERATE BUSINESS, GO GET NEW CUSTOMERS!
    YOU SHUT THE HELL UP AND QUIT RUNNING YOUR MOUTH!

  11. #24
    Join Date
    Sep 2004
    Location
    Kansas City, Kansas, United States
    Posts
    13,833
    30rb wants 7.6* superheat.

    11 is high



    Quote Originally Posted by Eastcoasttech View Post
    Well first I pulled 83 # of gas out. We had the coils replaced and recharged with 80 lbs because that's all we had at the time. There are four compressors and the problem is across all sets and if the coils are six feet across then two feet get warm and the remaining four stay cold. Walking on top of the unit, the right side farther away from the header is blowing cold while the header side blows warm/hot. It's almost like the refrigerant isn't making it across to the other side and only going in and out like the coil is "backwards". The display shows 11 degrees SH
    I WILL SELL WORK,GENERATE BUSINESS, GO GET NEW CUSTOMERS!
    YOU SHUT THE HELL UP AND QUIT RUNNING YOUR MOUTH!

  12. #25
    Join Date
    Jul 2003
    Location
    Orange County N.Y.
    Posts
    1,176
    Quote Originally Posted by supertek65 View Post
    30rb wants 7.6* superheat.

    11 is high
    Which would make it look to me like it was undercharged, unless there was a high load on the system.

    Check the subcooling, as others have said, it doesn't take much to overcharge. There are 10 or so needle thin holes in each one of those horizontal runs across the length of the coil and a piece of dessicant will create havoc. If you are sweating, common sense tells me that you have a pressure drop,

    ...Ron
    Roof Rat

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