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  1. #1
    Join Date
    Jul 2004
    Hey guys, I've got a good one. Walkin freezer, 404a, Copeland Diskus compressor. Pressures good, and oil pressure switch recently changed. Temps good, sight glass 90% full at start to 30% by completion of cycle, about 12 minutes. Every 5 to 6 weeks oil pressure switch trips. Oil pressure 45lbs. constant above suction pressure. No crank case heater, unit pumps down.Unit has been in operation for 6years.

  2. #2
    Join Date
    Feb 2004
    Home is Azle Texas, work in Dallas-Fort Worth & surrounding areas.

    Why was oil pressure switch changed? Was it tripping before? If this is a sentronic,check the O rings on the transducer. A small cut or nick can give eratic operation.
    May get better responce by posting this in refrigeration forum.
    Life as an adult is much like life in kindergarten - If I make it through the day without crying or hitting some one, then it was a good day!

  3. #3
    Change the oil in the compressor. While you've got the screen out at the bottom of the compressor ...CLEAN IT!!!
    Also check that "o-ring" that rabram mentioned. In case your not using the Sentronic, go get one and put it in.

    Also, when this switch trips, what is the level of your oil in the sight glass when you arrive?
    If there is oil in the glass when you arrive and the OPS is tripped... do you think you could have a bad contactor feeding the compressor?

    Your doin em a favor by changing the oil anyway .... I just dont believe in "nuisance trips". There's a reason behind a triped control.

  4. #4
    Join Date
    Sep 2001
    East Stroudsburg, PA
    Oil starts out at 90% in the SG, but drops to 30% in 12 minutes????

    You've got issues that don't involve replacing controls or oil.

    Are you a technician?

  5. #5
    Join Date
    Jul 2004

    "Oil pressure switch trips"

    Thanks for your feedback guys! The problem with the walkin freezer tripping on oil pressure didn't start out as my problem... I just heard other techs. talking about it and decided investigate. (I Love A Challenge.) Let us back up a little. (1) The pressures 16 to 21 suction on 404a. (2) High side 190 to 250. (3)Superheat around 8 degrees. (4)Oil pressure always 45lbs. above suction---ALWAYS. (5) Temperature around -11 in freezer. (6) EVERY 5 to 6 weeks, like a clock trips on "Oil Pressure". (7) Outdoor temp warm or cold doesn't seem to matter. Unit has done this (6) times that I know of and I'm the 5th. tech. I have never been the one to see it after it went down, so I haven't seen the sight glass. And anyone that has just reset it wasn't interested enough to look. (I took this one on because they want to replace compressor.)

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