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  1. #1
    Join Date
    Jun 2005
    Posts
    77
    My new 2 ton Ruud UAKB 024JAZ condensor copeland scroll compressor is making a loud hum that comes and goes but is there most of the time. My installer and 3rd party tech believe its because we used the .059 piston that came with the Apollo SA3024 air handler. The RUUD manual calls for a .057 piston.

    My concern is that it ran quiet as a kitten for 4-5 days before It started making the noise. Seems like it would have started right away??

    I have shut the system off. Tomorrow evening we are going to install the new .057 piston, vacuum the system down to 500 microns and recharge with R22.

    What if anything has to be done about the compressor oil?? Is that removed during the vacuum process?? The 3rd party tech says the oil isnt removed during the vacuum??


  2. #2
    Join Date
    Feb 2005
    Posts
    344

    Thumbs up Oil

    This is generally correct. The evacuation process usually does not remove an appreciable amount of oil.


  3. #3
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,376
    Be sure a new liquid line drier is installed.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  4. #4
    Join Date
    Jun 2003
    Location
    Hell Hole Swamp
    Posts
    4,180
    [QUOTE]Originally posted by mikeinva
    My concern is that it ran quiet as a kitten for 4-5 days before It started making the noise. Seems like it would have started right away??[QUOTE]

    You have cause for concern, I cant see a piston oversized by .002 being the cause of a compressor noise, not sure how your guys came up with that theory?

  5. #5
    Join Date
    Feb 2005
    Location
    Alabama
    Posts
    534
    Trial and error swamp, plus experience with mis-matched piston sizes. Using a #59 piston in an airhandler when the condensor requires a #57 is basically allowing too much freon into the evap coil and not enough in the compressor, resulting in excessive noise. I see this alot on Trane and Carrier systems. Change the piston, pull a GOOD vacuum (400 microns), recharge the system using a charging chart and 9 times out of 10 the problem is resolved.
    "If you can't fix it, don't break it."

  6. #6
    Join Date
    Sep 2004
    Posts
    172
    The scrolls especially the later models with the internal releif will make noise if there is a high side restriction or a severe overcharge and the high side pressure exceeds 300psig. The releif is operating, look for fluctuation in high side gauge it should kick down from around 300 to around 260 275 every few minutes, the compressor will self destruct in short order if the condition is not remedied. What were the pressure readings and outside ambient when they were checking it. Some techs are used to working on older R22 units with Reciprocating compresssors where 300psig high side and more at above 90f ambient would be considered normal, it just will not work on a late model scroll the little fella will come apart. Very little oil is recovered when vacuuming a system and what little does come out will not hurt these systems, they hold a lot of oil and a bit less makes little to no difference. Ask those guys if they check charge level by superheat method I am sure they will weigh in the proper amount but you really need someone to do a airflow and superheat check to make sure operating parameters are normal for this unit.

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