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  1. #1
    Join Date
    Feb 2010
    Location
    San Antonio
    Posts
    3

    RTAA Oil Pressure Problem

    Guys- we have a RTAA300 that has been tripping on oil flow. With the service bulletins we have, we found out that the compressor won't unload. We went through the service bulletins and replaced the load solenoid. Still starts loaded. I have read about a lip seal problem on these 100 ton compressors. Does anybody know if there is a service bulletin on that? One of the other compressors has a plate under the load and unload solenoids. Don't know what that is for, either.
    Yes, I'm new. Thanks.

  2. #2
    Join Date
    Mar 2010
    Location
    Va.
    Posts
    180
    This service bulletin is for lip seal problems with the 100ton compressors. Can you provide the serial number? Can you provide more information on what the pressures and amps are on start up? Does the compressor lock out on oil flow at start up or after the compressor is running for a while?
    Attached Files Attached Files

  3. #3
    Join Date
    Oct 2010
    Posts
    28
    1. the reason is tripping on oil flow is because the oil is being flush out from the oil separator (sump) due to hi discharge pressure being that the compressor is starting loaded.

    3.blown lip seals
    Bearing Cavity
    Pressure
    Gradually increase
    to approx. discharge
    pressure
    Gradually
    increase to approx.
    discharge pressure
    Gradually increase to
    approx. discharge pressure

  4. #4
    Join Date
    Mar 2010
    Location
    Va.
    Posts
    180
    The oil flow switch senses pressure drop across the oil filter and oil solinid. If the pressure drop is more than 50# the switch will open. High dischrge pressure at start up increses oil velocity which can cause a high pressure drop thru the filter.

  5. #5
    Join Date
    Jan 2009
    Location
    Not in Iran
    Posts
    1,091
    if the machine starts loaded, might want to check ur seals,. maybe worn.,
    or like what was already posted., high discharge pressure, oil filter clogger, dont know reccommend pd across filter., in iom., also check oil solenoid at compressor
    no signature blast'em man blast'em
    !!!KILL THE TERRORIST!!!

  6. #6
    Join Date
    Feb 2010
    Location
    San Antonio
    Posts
    3
    Phisher- the S/N: U98H02252. The discharge pressure starts above 200 and quicly climbs to 350 PSIG. The amps are 50% of FLA right after startup. The amps and pressures rise even during the 30 second unload period at startup.
    The compressor locks out on oil flow after about 2-3 minutes.
    Thanks for the bulletin-that looks like what I need.

  7. #7
    Join Date
    Mar 2010
    Location
    Va.
    Posts
    180
    Ther is a condenser fan upgrade for chillers built prior to July 1998. The upgrade starts condenser fans faster to lower the head pressure on start up. Your chiller was built prior to July 1998. High head pressure is whats tripping the circuit off on low oil flow. I'm attaching the bulliten that explanes the upgrade. A shorted condenser fan motor can cause the same probelm. The fan motors are powered thru the same fuses. If one motor shorts out and blowes the fuses it can keep other fans from runnig which makes the problem worse. I would check the fuses first.
    Attached Files Attached Files

  8. #8
    Join Date
    Mar 2004
    Location
    ottawa canada
    Posts
    2,045
    He already said the compressor is starting loaded , no amount of fans or staging eproms is going to fix that . The amperage should be less than 40% at start up period .
    The 64 roars to life Whoo hoo ...shes a rolling chassis .
    You bend em" I"ll mend em" !!!!!!!
    I"m not a service tech.. I"m a thermodynamic transfer analyst & strategic system sustainability specialist
    Best Austin Healey In Show twice in 2013 .....All those hrs paid off .

  9. #9
    Join Date
    Mar 2010
    Location
    Va.
    Posts
    180
    You are absolutly correct graham. I'm just giving rsneck some other things to look at if the lip seal checks out good. The oil flow switch is opening from high condenser pressures wheather it's from starting loaded or fans not running.

  10. #10
    Join Date
    Aug 2006
    Location
    Mixing oil and fire with a big spoon.
    Posts
    4,355
    Quote Originally Posted by rsneck View Post
    ...One of the other compressors has a plate under the load and unload solenoids...
    anybody else see this?

    describe 'plate' to us.

    there should only be gaskets, kind of a paper/fiber type...not metal. and only 1 of each under each solenoid. metal 'shims' or thin pieces of metal are usually used to test for a leaking slide valve piston. they are then REMOVED and new gaskets installed. with this 'plate', the compressor can not unload and it can only load up depending on the severity of the leaking piston.
    "Mother" is the name for God on the lips and hearts of children....The Crow

  11. #11
    Join Date
    Mar 2010
    Location
    Va.
    Posts
    180
    Check out the "RTAA lip seal" PDF and you will see the plate he's referring to. It's a retrofit to repair a leaking lip seal.

    rsneck, If the compressor your working on is a 100 ton compressor built in 98 then chances are good that you will need the lip seal re-route kit.

  12. #12
    Join Date
    Aug 2006
    Location
    Mixing oil and fire with a big spoon.
    Posts
    4,355
    ahhhhhh...block....plate....potato....potatoe....a nybody remember dan quayle?
    "Mother" is the name for God on the lips and hearts of children....The Crow

  13. #13
    Join Date
    Aug 2010
    Location
    Memphis
    Posts
    343
    The plate under the solinoids is part of the lip seal kit. Also, if I remember right, should have a 1/4 or 3/8 line running from it to the underside of the compressor. Are your solinoids working? Check your differential pressure across your filters and of course head pressure.

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