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  1. #14
    Join Date
    Nov 2007
    Location
    Mississippi
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    1,401
    Quote Originally Posted by Six View Post
    Im almost positive loaded is de-energized.

    Y2 doesn't connect straight to the unloader.

    That said letting a thermostat load and unload a compressor is a bad idea.

    Run that thing unloaded long enough and you'll be replacing it.

    Does it have a Sentronic oil pressure unit ? Ive got two antique 30 ton york splits with new Copelands in them. Their not staged by the T-stats anymore.

    Remember to use crankcase pressure to check oil pressure, not suction.
    I used crankcase and oil pump to check pressure ( same place oil press safety is hooked to). I dont know what a Sentronic oil pressure unit is.

  2. #15
    Join Date
    Apr 2012
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    Paper Street Soap Company
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    2,304
    Quote Originally Posted by socotech View Post
    I used crankcase and oil pump to check pressure ( same place oil press safety is hooked to). I dont know what a Sentronic oil pressure unit is.
    Oil pressure control for Copeland Compressors. Should be a module on the front of the compressor with a sensor tied into the oil sump.

  3. #16
    Join Date
    Nov 2007
    Location
    Mississippi
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    1,401
    No module Six.

  4. #17
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,945
    So, it's just a mechanical control. No biggie, we see them every day.

    3/4 glass is a shade high, but acceptable. That low oil pressure is bugging me.


    I typically see an unloader controlled with a low pressure control, but there are other ways.

    I'd grab a full set of system readings, map out a wiring diagram and something will probably jump out at you.

  5. #18
    Join Date
    Dec 2005
    Posts
    1,923
    Quote Originally Posted by socotech View Post
    ...Yes system is dirty.
    You may want to pump it down and check the oil filter screen.

    Also, there may be trash in the load/unload chamber so that the needle does not seat/seal well or tightly. Thus, the unloading piston chamber is exposed to the suction side and makes it running unload.

    https://opi.emersonclimate.com/CPID/...AEB/ae1278.pdf

  6. #19
    Join Date
    Apr 2012
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    Paper Street Soap Company
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    2,304
    I think Carlyse has the jump on Copeland for better load and unloading of semi hermetic compressors.

  7. #20
    Join Date
    Nov 2007
    Location
    Mississippi
    Posts
    1,401
    Thanks for the help. I'll let you know what I come up with.

  8. #21
    Join Date
    Nov 2007
    Location
    Mississippi
    Posts
    1,401
    Changed the oil three times. Oil was nasty. Replaced suction core and liquid line drier. Checked suction screen. Its now running with 50 psi oil diff. Loading and unloading properly ( low voltage was wired wrong). All seems good except high superheat (35*) and low subcool (5*). 74 suction 317 liquid line. I know probably still undercharged, just wanted to let it run a while and check it after space has cooled.

  9. #22
    Join Date
    Sep 2004
    Location
    Kansas City, Kansas, United States
    Posts
    13,833
    35* at the compressor is not that bad!
    what is 317 liquid line?
    do you have 75# suction or 75* suction line????????
    I WILL SELL WORK,GENERATE BUSINESS, GO GET NEW CUSTOMERS!
    YOU SHUT THE HELL UP AND QUIT RUNNING YOUR MOUTH!

  10. #23
    Join Date
    Nov 2007
    Location
    Mississippi
    Posts
    1,401
    75# suction line
    317# liquid line

  11. #24
    Join Date
    Jun 2011
    Location
    Detroit vicinity, Michigan
    Posts
    79
    I'm betting on a plugged condenser.

  12. #25
    Join Date
    Apr 2012
    Location
    Paper Street Soap Company
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    Quote Originally Posted by socotech View Post
    Changed the oil three times. Oil was nasty. Replaced suction core and liquid line drier. Checked suction screen. Its now running with 50 psi oil diff. Loading and unloading properly ( low voltage was wired wrong). All seems good except high superheat (35*) and low subcool (5*). 74 suction 317 liquid line. I know probably still undercharged, just wanted to let it run a while and check it after space has cooled.


    Two TxVs in that AHU or just one ?

    I've got an old York 15 ton that splits off into two circuits at the AHU with two solenoid valves.

    Sounds undercharged a bit and maybe you're dealing with a lot of load.

  13. #26
    Join Date
    Nov 2007
    Location
    Mississippi
    Posts
    1,401
    High load (80*). One txv and no solenoid. 100*+ ambient. There is possibly some condenser air recirculation too. It has a solid brick wall on three sides about 20" out.

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