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  1. #14
    Join Date
    Dec 2011
    Posts
    107
    Power down unite ,then power up exv should move,you should see stem move.In pre start valve should go to 250

  2. #15
    Join Date
    Feb 2003
    Location
    Wichita Ks
    Posts
    1,404
    you can put in test and move the valve all the way open and close. BUT it still can hang up while in operation when there is a pressure drop. check your subcooling and exv postion while running low evap pressure. that will giave you an idea if the valve is hanging up.

  3. #16
    Join Date
    Dec 2011
    Posts
    107
    Yes there is a oil dp.check oil return line,strainer pressure drop .Some time if discharge s/h is to low it will cause foaming in oil and optic sensor will see low oil .adjust ball valve in front of oil return valve to keep dis s/h up and out of low dis s/h

  4. #17
    Join Date
    Jun 2012
    Location
    West Virginia
    Posts
    22
    Low evap refrigetant pressure...(I was just told that something like 28 or so tubes are pluged instead of 5) I believe there is adequate water flow tho, I got the exv to open and close in test mode. not long after my compressor is loading, circuit goes into low pressure hold and then unload.. it unloads to 0% slide target and reads slightly into the neg on the slide position sensor so I guess I am unloading ok... suction pressure eventually falls and shuts circuit down. I think the next thing I am going to try is pumping down and changing my filter cores, what do you guys think..

  5. #18
    Join Date
    Feb 2003
    Location
    Wichita Ks
    Posts
    1,404
    watch the exv through the sight glass while it is running. was it open? what did the display show (position)? what was the subcooling?

  6. #19
    Join Date
    Mar 2009
    Location
    Mid-Mo
    Posts
    3,425
    Are you getting any pressure/temperature drop across the driers?

  7. #20
    Join Date
    Dec 2011
    Posts
    107
    I think there may only be 100-150 tubes.The tubes are also rolled at the center tube support.And make sure chiller can start pump all long,or drain in winter.

  8. #21
    Join Date
    Jun 2012
    Location
    West Virginia
    Posts
    22
    I couldnt see exv move when it was running. I think it said 3000 steps and 0 slide with high subcooling.(I will log all of this down monday) I couldnt read much pressure drop at the driers but compressor was unloaded.

  9. #22
    Join Date
    Jun 2012
    Location
    West Virginia
    Posts
    22
    I have checked the exv in the test mode and it is easy to see it move. When running, circuit controler says exv was at 3384 but in the sight glass it still looked like it was closed. I ran exv to 3384 in test and it was very obvious that it was open. Here is info I got from when I reset and it tripped today "ewt was 85 deg when unit started and it tripped between 5-10 mins" LWT 80.7 EWT 80.9 OAT 76.8 EVAP 24.9 PSIG COND 152.9 PSIG LI

  10. #23
    Join Date
    Jun 2012
    Location
    West Virginia
    Posts
    22
    LIQUID 160.8 PSIG SUCTION TEMP 57.7 DISCHARGE TEMP 178.3 LIQUID TEMP 84.9 DISCHARGE SH 65.7 LL SC 30.9 EXV 3384 EXV STATE PRESSURE, SLIDE 23.4 SLIDE TARGET 32.0

  11. #24
    Join Date
    Feb 2003
    Location
    Wichita Ks
    Posts
    1,404
    I would bet it is hanging up while running. I have had this happen on a good number of them. you might trade exv driver board with the one on the other circuit to verify the board is ok.

  12. #25
    Join Date
    Jun 2012
    Location
    West Virginia
    Posts
    22
    Ok I will switch the drivers and see what happens. I wonder why it always moves in test mode? Sounds like you work on a lot of mcquay chillers freonrick

  13. #26
    Join Date
    Feb 2003
    Location
    Wichita Ks
    Posts
    1,404
    when in test mode there is no pressure differential across valve or very little compared to when it is running.

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