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  1. #14
    Join Date
    Aug 2013
    Location
    Florida
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    Thread Starter
    Quote Originally Posted by lynn comstock View Post
    Internal Pressure Relief valve.

    Trip pressure depends on the difference between the high and low side pressures and it varies with refrigerant and compressor application. It takes a very high pressure difference. If the trip point pressure difference is regular I would think that it is the valve defective...Pretty rare.

    A slug of refrigerant and/oil can cause a trip on startup or while running if the suction line traps liquid somewhere and periodically releases a slug into the compressor. Careful observation of the pressures at the point of the trip can help differentiate the failure mode. Keep notes when strange things happen. If the trip point pressure difference is NOT regular i would take a hard look at the suction piping for unintended oil traps. A suction line accumulator would solve this problem.
    Thanks. I have definitely learned something new. I originally thought it sounds like a pressure relief but didn't know they were equipped with them internally so I was definitely thrown for I loop. I started to figure something was worn internall in the compressors.
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  2. #15
    Join Date
    Aug 2013
    Location
    Omaha
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    Quote Originally Posted by RichO View Post
    Thanks. I have definitely learned something new. I originally thought it sounds like a pressure relief but didn't know they were equipped with them internally so I was definitely thrown for I loop. I started to figure something was worn internall in the compressors.
    If they didn't come with CRO valves for the freezers or anything like that from the factory heres what I would do...

    Either add that OR...a liquid solenoid at the condensing unit. Not pump down...just a valve that opens and closes with the compressor (wired in parallel with the condensing unit)

    What can happen in freezers is during defrost or an off cycle, all the charge equalizes thru the crap tube and ends up in the evap.

    When the comp cycles on next your head can go thru the roof depending on the brand/configuration for a minute until all the refrigerant is circulating properly again.
    Thats very hard on the compressor and thats why freezers usually have that CRO valve to keep that from happening.
    Or just a solenoid that closes in the liquid line when the comp shuts off can help alot too.

    Just an idea

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