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  1. #1
    Join Date
    Jan 2001
    Posts
    758

    compressor unloading

    can someone explain what is actually happing inside compressor when compressor unloads. was working on large trane tin can. it had solenoid inside
    cover.when compressor loaded suction went down amp draw up but never totally understood what happens intenally. i guess refrigerant is being bypasses internally. any tricks to troubleshoot/repair. anybody know of any good compressor schools.

  2. #2
    Join Date
    Apr 2006
    Location
    mechanical room
    Posts
    1,255
    whats the compressor type, model #, probably either the hot gas bypasses and dumps back into the suction side, or a piston blocks the suction not allowing the compressor to pump any refrig. thus not doing any work. thats about as simple as i can describe it

  3. #3
    Join Date
    Jan 2008
    Location
    Dallas ,Texas
    Posts
    3,700
    It`s kinda like a Dodge MDS engine. When your in the city it uses half of it`s capacity let`s say it`s a 6 cylinder . 3 in the city and 6 on the highway.
    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.

  4. #4
    Join Date
    Jul 2009
    Location
    In a mechanical room....
    Posts
    1,887
    It depends screw most via slide valve, semi hermetic have a few different ways, Centrifugals by freq and turning vanes modulation etc...........
    “It takes courage to grow up and turn out to be who you really are.”

    - E.E. Cummings

  5. #5
    Join Date
    Sep 2004
    Location
    Kansas City, Kansas, United States
    Posts
    13,832
    semis use either hot gas bypass which is inefficient or suction unloading
    both can be operated mechanically, electric unloader, pneumatic unloader or oil pressure unloader.
    i have not seen one but i have heard of some machines that LOAD when powered up????
    i know that on trane E compressors that operate with oil pressure that they start UNLOADED

    have fun




    Quote Originally Posted by chrishvacman View Post
    It depends screw most via slide valve, semi hermetic have a few different ways, Centrifugals by freq and turning vanes modulation etc...........
    I WILL SELL WORK,GENERATE BUSINESS, GO GET NEW CUSTOMERS!
    YOU SHUT THE HELL UP AND QUIT RUNNING YOUR MOUTH!

  6. #6
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,395

  7. #7
    Join Date
    Sep 2004
    Location
    Kansas City, Kansas, United States
    Posts
    13,832
    hi JP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

    i would like to unload a couple of my daughters!!!!!!
    they are a pain in the arse


    Quote Originally Posted by jpsmith1cm View Post
    http://www.hvacrinfo.com/ae_index.htm


    Scroll down to section #21.

    There you will find Copeland's AE bulletins on capacity control.
    I WILL SELL WORK,GENERATE BUSINESS, GO GET NEW CUSTOMERS!
    YOU SHUT THE HELL UP AND QUIT RUNNING YOUR MOUTH!

  8. #8
    Join Date
    Aug 2000
    Location
    USA
    Posts
    4,986
    In a nutshell, the compressor is moving less volume of gas as it unloads. Be it by frequency, guide vanes, slide valve or rendering a few cylinders out of action. JMHO
    Your poor planning does not constitute an emergency on my part!!!!

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