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  1. #1
    Join Date
    Jun 2005
    Posts
    77
    RUUD 2 ton UAKB 024JAZ condenser with Appolo SA 3024 air handler. Air handler came with .059 piston. Condenser compressor ran quiet as a mouse for 4 days and now its making a racket.

    RUUD manual piston chart shows 57 piston when mated to RUUD air handler.

    Is 57 the same as .057??

    Is .002 enough difference to make any difference??

    Im at a loss and local heating and plumbing company blamed the .002 as soon as I questioned it. I think theyre stupid.

    Im more inclined to think non-condensables?? Evac, pump to 500 microns and recharge. If that doesnt work replace compressor.

  2. #2
    Join Date
    May 2003
    Location
    Dixie
    Posts
    1,344
    well are you gonna give us some pressures & temps?

  3. #3
    Join Date
    Jun 2005
    Posts
    77
    going to change piston from .059 to .057 vacuum and recharge the system.

  4. #4
    Join Date
    Feb 2005
    Location
    Alabama
    Posts
    534
    Originally posted by frigetater
    well are you gonna give us some pressures & temps?
    Not needed. The difference between .057 and .059 is enough to give inaccurate readings resulting in an improper charge which can cause problems.
    "If you can't fix it, don't break it."

  5. #5
    Join Date
    Jun 2005
    Posts
    77
    Thank you Duct Dr. Gonna put in a .57 and vacuum to 500 microns and recharge.

    Will that really need a new filter dryer??

  6. #6
    Join Date
    Feb 2005
    Location
    Alabama
    Posts
    534
    If the lineset is new, then maybe not. But if it's existing copper then yes install a new dryer.
    "If you can't fix it, don't break it."

  7. #7
    Join Date
    Jun 2005
    Posts
    77
    My only concern with changing piston from 59 to 57 is why did the compressor run quiet as a kitten for 4-5 days before it started the loud humm?? Seems like if the .002 difference in piston size is that critical then it would have been a problem the first time the unit was started??

  8. #8
    Join Date
    Feb 2005
    Location
    Alabama
    Posts
    534
    Not in all cases. Some systems can take 24 to 48 hours to fully equalize and start cycling normally. Kinda like a car low on oil without an oil pressure guage, you won't know it till you hear the valves ticking but its been low for quite some time. Some compressors sound different when low on charge, but you may not hear it right away.
    "If you can't fix it, don't break it."

  9. #9
    Join Date
    Jul 2004
    Location
    midwest
    Posts
    2,868
    I doubt the piston is your problem but you might fix it in the process of changing it. Since you have to pump it down I would put the correct piston in but my experiance has been that you will not notice much difference in that close of a match.

  10. #10
    Join Date
    May 2003
    Location
    Dixie
    Posts
    1,344
    recover the refer., change the piston, and since you have the system opened, change the dryer, pressure test, pull a deep vac., weigh in proper charge, then give some readings. but I still don't think the piston is your problem

  11. #11
    Join Date
    Apr 2004
    Posts
    7,680
    Weighing it in may be ok but remember he isnt using a RUUD coil so it will not be as accurate as you want. Granted the indoor coil carries very little liquid refrigerant compaired to the rest of the system. Also the piston may or may not help, .002 isnt very much and will not affect the performance by much if at all but the actual problem has still not been stated. So far all I see is he is complaining of a noise issue.

  12. #12
    Join Date
    Jun 2005
    Posts
    77
    System is cooling and dehumidifying my house great. The scroll compressor is too noisy and the noise is being transmittred into the wall thru the lineset.

    Maybe liquid slugging?? maybe just bad compressor. Im sure there have been bad ones shipped. I have another tech coming to look at it and maybe this one will have some level of competence.

    It took the parts counter lady to check the ARI to inform me that the coil and condenser were rated to be used together. Im sure the orifice isnt an issue.

    Im a homeowner but Im not doing any of the work. Unfortunately because the techs Ive dealt with are idiots I am doing some research for myself. Lots of thanks to those on this website that have taken the time to make constructive comments/suggestions.

  13. #13
    Join Date
    Apr 2004
    Posts
    7,680
    Ok...here goes.

    When a compressor (specificly a scroll) gets noisy its generally not a mechanical issue, its a refrigerant issue. Most often overcharged. If the airflow is weak the techs will unknowingly try to compensate by adding refrigerant rather than fxing the issue. The piston is oversized but not by much, this in combination with the overcharge can be just enough to make the compressor noisy.

    On warmer days (just recent), the high temperature makes the high pressure go up. When it does, it forces more refrigerant into the evaportator flooding it. Well, if the unit is overcharged you may very well start slugging the compressor on the hottest days. You dont have a compressor problem.

    Your problem is the unit is either overcharged, lacking airflow or both. While they are at it, they should put the right piston in for your sake. If you dont like your technician, call another but understand you will have to pay the other company becuase 1 its not a warranty issue with the equipment (thats abuse) and other dealers do not provide labor support for the original installers goof ups.

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