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  1. #1
    Join Date
    Apr 2011
    Location
    South Dakota
    Posts
    15

    WOW this so stupid

    I just replaced two compressors on a 40 ton Trane rooftop unit. wired it up and when i turned the breaker for "c" compressor, which is one of the two i replaced ( c & d), "C" compressor runs for about30 to 50 secs. then shuts off. Outside air temp is about 80f and this is stage two should be running... I dont have good shematics and we're running Johnson Controls. Stage 1 &4 run great on the other side of the unit, but according to he diagram, A & C should be on afterA M/n # is RAUCC40EBX what's keeping the unit from running normally? I charged the unit with appropriate charge of r22? Hep Meh Pleeze.

  2. #2
    Join Date
    Apr 2012
    Location
    Paper Street Soap Company
    Posts
    2,304
    Do you have guages on it ? Sounds like its pumping down and shutting off on LP or even tripping on HP.

    Do you have low voltage inputs from the EMS ?

    Prints or no prints if your changing comps on that unit you should be qualified to troubleshoot a basic compressor circuit.

    If you didnt change the drier it could be plugged or the power cap might be bad so its pumping down.


    Also OAT doesnt dictate capacity. You need to check inputs to unit from building ems.

  3. #3
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,791
    Moved to Tech to Tech.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  4. #4
    Join Date
    May 2011
    Location
    Spring City, Pennsylvania, United States
    Posts
    191
    Is this one of the units.where the HP switch is on an angle valve that needs to stay a crack open? I've seen that happen a lot where people close that valve and this happens.

  5. #5
    Join Date
    Sep 2006
    Location
    Ohio
    Posts
    498
    Are you sure there is a call for the compressor? What are the amp draws and the pressures. I just replaced the same two compressors on a 40 ton RAUCC. Had to drain off some of the oil after startup. Did you check rotation of that compressor?

  6. #6
    Join Date
    Oct 2009
    Location
    Mukwonago, WI
    Posts
    250
    What caused the compressor to fail? what is causing the compressor to shut off? Simple diagnostics to figure out why the compressor is shutting off.

  7. #7
    Join Date
    Apr 2011
    Location
    South Dakota
    Posts
    15

    Thumbs up Found it!

    Quote Originally Posted by ruuufuhbock View Post
    Is this one of the units.where the HP switch is on an angle valve that needs to stay a crack open? I've seen that happen a lot where people close that valve and this happens.
    Sorry I havent been back on this site for a while to reply, I've been extra busy since the passing of a co-worker recently. But after I posted the thread, I went back up to check it out further and I found I had accidentally back seated this valve all the way which caused the problem you mention here. I was sure i had left it a crack open but hadn't. At least I found it right away and went on to finish the job and all is well.

  8. #8
    Join Date
    May 2011
    Location
    Spring City, Pennsylvania, United States
    Posts
    191
    Wow I finally got one!!! Lol bottoms up tonight!!

  9. #9
    Join Date
    Jun 2006
    Location
    midwest
    Posts
    126

    COMPRESSORS

    FIRST STAGE IS A AT 25%, THEN A +,C AT 50%,A,C,D AT 75%,B COMPRESSOR IS THE FINAL 4TH STAGE ABC+D=100%.NO CONTROLS

  10. #10
    Join Date
    Jun 2006
    Location
    New Jersey
    Posts
    4,340
    Quote Originally Posted by ruuufuhbock View Post
    Wow I finally got one!!! Lol bottoms up tonight!!
    About time!

  11. #11
    Join Date
    May 2011
    Location
    Spring City, Pennsylvania, United States
    Posts
    191
    Quote Originally Posted by ascj View Post
    About time!
    I might even have a tee shirt made to mark the occasion!

  12. #12
    Join Date
    Jun 2006
    Location
    New Jersey
    Posts
    4,340
    Quote Originally Posted by ruuufuhbock View Post
    I might even have a tee shirt made to mark the occasion!
    Just make sure when your infront of the customer....you're in proper uniform.

  13. #13
    Join Date
    May 2011
    Location
    Spring City, Pennsylvania, United States
    Posts
    191
    I'll wear it underneath the collared shirt at all times like superman

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