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  1. #1
    Join Date
    Mar 2014
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    Is My Diagnosis Correct

    I went today to check a TEMPSTAR 3 Ton, 13 SEER Split System Heat Pump with matching TEMPSTAR indoor coil.
    An inspection of the coil revealed it was pretty much frozen.

    After the indoor coil thawed out and with the system running in cool mode, I observed the low pressure
    was much lower than what the performance table indicated. At 85 degrees outdoor dry bulb, 57 degrees
    wet bulb and 75 degrees indoor dry bulb the low pressure should have been 129 pounds. The low
    pressure read 95 pounds (saturated temperature 28 degrees) which is what was freezing up the indoor
    coil.....The high pressure read 313 pounds which was right on target with the performance table.

    It appears to me that the TXV Valve has went defective.

    Any other advise is highly appreciated

    Thank You in advance for your feedback!

  2. #2
    Join Date
    Apr 2016
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    Parts unknown
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    Don't you know nobody will talk to you unless you give SH and SC. this time it's actually applicable....

  3. #3
    Join Date
    Jan 2011
    Location
    Portland, OR
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    At least you got WB readings. Try taking the txv bulb off and see if anything changes. SH, SC, airflow correct?

    Sent from my SM-G920V using Tapatalk

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  5. #4
    Join Date
    Jul 2012
    Location
    WA
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    Could be airflow. Need sh/sc.

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  7. #5
    Join Date
    Jan 2004
    Location
    PA
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    75Db and 57WB, no real indoor load. The RH is 31.6, and the DP is 42.8

    While you could have a TXV problem, are you sure you were moving a min of 400 CFM per ton. IS the indoor unit a VS blower unit. If so, was it set to do a slow ramp up.
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    How many times must one fix something before it is fixed?

  8. #6
    Join Date
    Mar 2015
    Location
    Medford, N.Y.
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    Yea,w/ SH&SC #'s you might find that the hi side press should be closer to 375-385psig and the system might be lo on freon. That TXV swap out will cost the customer $-$. Is there a SightGlass on this unit?
    IDK if you are correct or not.
    Last edited by beenthere; 06-01-2016 at 05:26 PM. Reason: Prices

  9. #7
    Join Date
    May 2001
    Location
    Kansas City
    Posts
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    If the subcooling is 8-12* then you most likely have a bad TXV. Pressures mean nothing without line temps on 410 with TXV. Pressures do look low though like its low on charge or TXV is clogged or lost the power-head charge and is all the way closed.

  10. #8
    Join Date
    Mar 2014
    Posts
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    I apologize for not furnishing the superheat/subcooling numbers.
    Subcooling was 10 degrees.

    Airflow is at 1200 CFM (3 Ton).
    When an attempt is made to add refrigerant the high pressure will climb, however the low pressure stayed at 95 pounds.
    Thank You for everyone's comments/advise!

  11. #9
    Join Date
    May 2001
    Location
    Kansas City
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    Bad or clogged TXV. Or the evap coil is dirty or airflow is bypassing coil.

  12. #10
    Join Date
    Jul 2012
    Location
    WA
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    Sounds like a partially plugged txv. How did you measure cfm? 1200 hundred is perfect, but not a realistic exact airflow.

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  14. #11
    Join Date
    Sep 2014
    Location
    Portland, Oregon, United States
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    I'm following this. Any good advice for identifying a txv issue vs low charge? High superheat etc..?

  15. #12
    Join Date
    Jul 2014
    Location
    Apache Junction, Arizona
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    If the airflow is i am assuming the indoor blower is direct drive being a 3 ton, any restriction in the return air flow like dirty filters or debris or dirty coil can do this.. the loss of the powerhead charge is plausible or even loose bulb not attached correctly... one post recommended removing the bulb and replacing it is a good idea see if is any changes and reattaching it to the correct o clock and nice and tight to the suction line would make sure it is opening and closing correctly. if not is probable bad txv I agree.
    "I never lie because I don't fear anyone. You only lie when you're afraid." - John Gotti

  16. #13
    Join Date
    Jul 2014
    Location
    Apache Junction, Arizona
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    Quote Originally Posted by Red Man View Post
    Sounds like a partially plugged txv. How did you measure cfm? 1200 hundred is perfect, but not a realistic exact airflow.
    I agree the cfm is basically off the unit data not actual field measurement.. if you ain't measuring it you are simply guessing.
    "I never lie because I don't fear anyone. You only lie when you're afraid." - John Gotti

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