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Thread: a problem unit

  1. #14
    Join Date
    Jul 2012
    Location
    sanger texas
    Posts
    21
    Quote Originally Posted by d.crowder View Post
    condensor coil clean as a whistle, no airflow restrictions what so ever, i changed the speeds on my indoor motor several time to see any change.. none that would make a huge difference... i have a idea but just a idea the 16 seer trane compressor has a bridge rectifier that opens and closes a little between first and second stage (one compressor) but im not quite sure how to check that. im still waiting on a call from trane talk to them once and he told me he'd call back...not a good sign
    besides my dc voltage from rectifier im not sure how to check if the compressor is open all the way

  2. #15
    Is the air handler in the attic? Is the attic insulated? If not this maybe your problem.
    Your return air needs to come from the high wall or ceiling. Then check pressures.

  3. #16
    Join Date
    Aug 2012
    Location
    Palmyra, Missouri, United States
    Posts
    224
    Bad TXV

  4. #17
    Join Date
    Aug 2012
    Location
    Hot Springs, Arkansas, United States
    Posts
    55
    Confusion Say, It take 1000 what it aint to find 1 what it is......

  5. #18
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,627
    Txv have replaced many on tranes .as for the 2 stage compressor disconnect y2 and watch your amp draw should change by about 30 % . also at 6 subcool might push it up a bit and see what the superheat does

  6. #19
    Join Date
    Nov 2011
    Location
    USA
    Posts
    377
    my first arrival 3:00pm (first day)
    my pressures @ 143/463psig
    40sh-6sc
    ambient temp 104'F
    delta t 19'F return temp 86'F supply temp 67'F
    wet bulb 78.3
    system shows symptoms of low charge due to high superheat and low subcool readings. condensor coil clean washed several times to make sure. decide to return in the morning to see what changes.

    The head pressure is around 70 psi higher than it should be for 104˚ ambient, according to the service literature. But the SH and SC do suggest undercharge.

    8:30am (second day) system maintaining
    my pressures 121/344psig
    35sh-5sc
    ambient temp 93'F
    delta t 19'F return temp 77'F supply temp 58'F
    compressor amp draw 13.5 fan motor amp draw 0.9 fan is on high speed.
    i decide to charge the system to get 10'F sc and drop my superheat and raise my subcooling at this point my main concern is my head pressure. i decide to return in the afternoon again to see my changes

    Head pressure is about right for 93˚ ambient

    3:00pm (second day)
    my pressures are fluxuating between
    154/520 and 149/500psig
    my subcooling and superhead are also doing the same (but much better)
    11-14'F sc - 13-16'F sh
    ambient 104'F

    The fact you were able to get decent SH and SC by adding refrigerant seems to eliminate the TXV. But the head is obviously way high now, and looks like it's due to low condenser air. You cleaned the OD coil. I'm wondering if the condenser fan motor is running the correct second stage speed???

  7. #20
    Join Date
    Jul 2012
    Location
    sanger texas
    Posts
    21
    Fan motor on particular unit isn't var. Speed or multi-speed, amp draw normal.. motor working within specs. The boss man says replace txv so I'm gonna do what I'm told, the customers out of town so I'm gonna replace the txv, drier and refrigerant next week. I'll post what happens.

  8. #21
    Join Date
    Jul 2012
    Location
    sanger texas
    Posts
    21
    Yup in the morning the system is fine and operating normally, im within my refrigerant curve but it gets all wonkified (technical term) in the afternoon lol

  9. #22
    Great information! I would rule out your non-condinsable, your discharge temp vs pressure is right on.

    So the 2 areas I would focus on:
    1) Solid column of liquid getting to the TXV (dryer most suspect, but any restriction in the liquid line should be considered - or flashing)
    2) TXV

    Good luck!

  10. #23
    Join Date
    Aug 2012
    Location
    willowick ,oh
    Posts
    261
    The 16 seer i believe has a two stage scroll compressor. By looking at your pressures it looks like it was in second stage but i would still check the switch in the outdoor unit.The only other thing is if it is a trane evap coil. there was a recall on a series of expasion valves. there is a service bulletin about it too through tranes comfort site. Run the serial #. The valves were made with moisture in the sensing bulb and run a 35 to 45 degree superheat. That looks like your problem to me. good luck remember TXV

  11. #24
    Join Date
    Aug 2012
    Location
    willowick ,oh
    Posts
    261
    Also what trane sometimes forgets to tell people is sometimes with the 15 to 20 seer outdoor units you must use a much larger indoor coil or ahu. trust me. Ive had to uninstall brand new equipment because of inadequate cooling. The smaller coils that are the same tonnage cannot properly handle the amount of refrigerant. Call trane tech support and run all of your #'s to rule it out.

  12. #25
    Join Date
    Aug 2012
    Location
    willowick ,oh
    Posts
    261

    Lightbulb

    Also what trane sometimes forgets to tell people is sometimes with the 15 to 20 seer outdoor units you must use a much larger indoor coil or ahu. trust me. Ive had to uninstall brand new equipment because of inadequate cooling. The smaller coils that are the same tonnage cannot properly handle the amount of refrigerant. Call trane tech support and run all of your #'s to rule it out

  13. #26
    Join Date
    Jul 2012
    Location
    sanger texas
    Posts
    21
    It's a matched size wise I did check on that, yeah boss man said replace txv so that's what I'm doing next week, we'll see how it goes... I personally have a hard time saying its the valve according to all my readings but I'm not sure what else it could be.

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