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  1. #14
    Join Date
    May 2007
    Location
    Central NJ Area
    Posts
    779
    Txv stuck open

  2. #15
    Join Date
    Jul 2012
    Location
    Dillwyn, VA
    Posts
    43
    TXV problem

  3. #16
    Join Date
    Jan 2012
    Location
    Fresno, ca
    Posts
    32
    Read the book on that cond. Unit. I know with some Carriers, they have to be running in high capacity or you'll get funny pressure reading. Also check if the indoor blower is running in high speed.

  4. #17
    Join Date
    Jun 2007
    Location
    Greenwood Indiana (Indianapolis)
    Posts
    420
    Sounds like more air flow is needed to me.
    As iron sharpens iron so one man sharpens another Proverbs 27:17 NIV84

  5. #18
    Join Date
    Feb 2010
    Location
    IL
    Posts
    120
    TXV Problem, Airflow is good at 700 CFM for a 2 ton. Newer systems call 350 CFM better dehumidification. Seems stuck open.

  6. #19
    Join Date
    Jan 2007
    Location
    Mn the state where absolutey nothing is allowed
    Posts
    1,312
    Quote Originally Posted by MIDCAM View Post
    I am working on a two stage heat pump with a varable speed air handler.
    The system runs about 1.5 deg S/C and about 2 deg S/H The delta T is 22 deg. A capacity check shows systems is operation at 122% of publish Capacity. Adding refregerant does not change the S/C much at all.
    My question is how is this possable? low subcooling and low S/H
    This is a matched system, and all test equiment was checked for accuarcy.
    Quote Originally Posted by skidoox800 View Post
    TXV Problem, Airflow is good at 700 CFM for a 2 ton. Newer systems call 350 CFM better dehumidification. Seems stuck open.

    the only way he's getting 122% rated capacity is that there is actually less airflow than the number he used in the capacity calculation.
    my boss thinks its possible to repeal the laws of physics

  7. #20
    Join Date
    Oct 2009
    Location
    Florida
    Posts
    162
    I believe your compressor is still in first stage. IIRC there's a five minute delay from signal sent to compressor engage in addition to the delays in some thermostats. I've seen those same pressure/temp/sh/sc conditions on a carrier two stage system that would not engage full capacity.

  8. #21
    Join Date
    Dec 2008
    Location
    indiana
    Posts
    17
    verify air flow using mini vane or equev.
    what is the amp draw at compresor
    is the evap coil / blower clean
    what is return wb and
    supply wb
    how did you figure capacity

  9. #22
    Join Date
    Dec 2011
    Location
    British Columbia, Canada
    Posts
    53
    have you tried testing the txv by heating and cooling the bulb?

  10. #23
    Join Date
    Jan 2007
    Location
    Mn the state where absolutey nothing is allowed
    Posts
    1,312
    its been 6 days, the OP hasnt been back, guess he fix it.?!?

    so we can all benefit, it'd be nice to here how these threads end up
    my boss thinks its possible to repeal the laws of physics

  11. #24
    Join Date
    Jan 2011
    Location
    Maryland
    Posts
    9

    Fixed

    Sorry for the delaying in posting, While I was on vacation, another tech replaced the indoor coil. After replacement the system ran at spec's 12 deg s/c 9 deg of s/h. althought the coil would frost evenly when the blower was off. We ran out of options and replaced the coil. I am requesting an RMA back to Carrier to have the coil tested. If I get anything back I'll post thier finding.
    Thanks all

  12. #25
    Join Date
    Nov 2011
    Location
    USA
    Posts
    333
    Quote Originally Posted by MIDCAM View Post
    We ran out of options and replaced the coil.
    Which options did you exercise?

  13. #26
    Join Date
    Jan 2011
    Location
    Maryland
    Posts
    9

    tXV

    The TXV was changed from the factory Danfoss to a Sporland, The equalize line was check for flow. All checked good. Air flow was double checked by checking pressure drop a crossed the coil. .58”wc

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