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  1. #1
    Join Date
    Mar 2013
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    Chicago
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    354

    Defective TXV causing compressor overload cycling ?

    Can a bad TXV cause the compressor to cycle on overload ?

  2. #2
    Join Date
    Jan 2006
    Location
    McQueeney, Texas
    Posts
    3,707
    Yes .

  3. #3
    Join Date
    Mar 2013
    Location
    Chicago
    Posts
    354
    What would the pressures exhibit if it was the txv causing the problem?
    I recommended to a friend to pull and weigh the charge and pull a vacuum and recharge, because its a completely new system, CU , Evap coil , Linesets and txv, all new.
    I didnt do the install it was another friend of his.

  4. #4
    Join Date
    Mar 2013
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    Chicago
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    354
    This must be a tough one ? Nobody , not even the pro's on this forum can offer any insight on this problem ?

  5. #5
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,704
    Quote Originally Posted by Bobe5531 View Post
    This must be a tough one ? Nobody , not even the pro's on this forum can offer any insight on this problem ?
    Mostly because you haven't given any real information about the problem.

    Saturated suction temp
    SH
    Saturated liquid line temp
    SC
    Indoor ambient temps, Db and WB of return and supply
    Delta across indoor coil
    Outdoor ambient temp
    Compressor amp draw
    Condenser fan amp draw
    Delta across outdoor coil
    Evap above or below condenser, and how far
    AHRI matched system or not
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  6. #6
    Join Date
    Mar 2013
    Location
    Chicago
    Posts
    354
    Quote Originally Posted by beenthere View Post
    Mostly because you haven't given any real information about the problem.

    Saturated suction temp
    SH
    Saturated liquid line temp
    SC
    Indoor ambient temps, Db and WB of return and supply
    Delta across indoor coil
    Outdoor ambient temp
    Compressor amp draw
    Condenser fan amp draw
    Delta across outdoor coil
    Evap above or below condenser, and how far
    AHRI matched system or not
    Good point . I dont have that data, yet. I guess I was just speaking in general terms as what a tech might see the system doing or not doing if there was a defective TXV.

  7. #7
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,704
    A TXV can fail in more then one way. So there are several different symptoms you could see, depending on what is wrong with the TXV.

    Apply for Pro membership. Lots of info in the Pro only forums.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  8. #8
    Join Date
    Nov 2007
    Location
    Mississippi
    Posts
    1,274
    High head
    Low suction

  9. #9
    Join Date
    Nov 2007
    Location
    Mississippi
    Posts
    1,274
    I just saw a 40 ton RTU do this last Friday.

  10. #10
    Join Date
    Sep 2002
    Posts
    12,195
    What "overload" is the compressor cycling on?

    Does the condenser fan motor stop or start when the compressor cycles on the overload?

    Is the amp draw exceeding the FLA rating?

    Is the compressor shell temperature exceeding the maximum rating?

    PHM
    ------





    Quote Originally Posted by Bobe5531 View Post
    Can a bad TXV cause the compressor to cycle on overload ?
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  11. #11
    Join Date
    Dec 2005
    Posts
    94
    Assuming that you mean the internal overload/temperaure protection device is opening after a period of hour or hours running. If the expansion valve is causing this indirectly it is because the superheat is too high. The valve is not open enough to allow sufficient cooling refrigerant to the compressor. If it is a basic residential unit this will usually happen if the SH is over 20 degrees. I used to have a lot of this problem when I worked in the desert, not so much in a cooler climate.

  12. #12
    Join Date
    Mar 2013
    Location
    Chicago
    Posts
    354
    Quote Originally Posted by Poodle Head Mikey View Post
    What "overload" is the compressor cycling on?

    Does the condenser fan motor stop or start when the compressor cycles on the overload?

    Is the amp draw exceeding the FLA rating?

    Is the compressor shell temperature exceeding the maximum rating?

    PHM
    ------
    Heres the only info I have on this one until I check it out myself :
    All new evap coil linsets CU. Installed about 5 weeks ago and has had this problem from day one.
    He claims that the comp is turning on and off on high pressure overload constantly. Sometimes it stays running for an extended period sometimes not. The guy is an electrician and claims that voltage is correct as well as amp draw. His buddy who installed it is supposedly 30 yr Hvac tech. The buddy suggests that it may be overcharged. He said he had two guys working on it at he same time.
    I know this is very vague and can see why you guys would need much more data to make any suggestions of a solution. I will try and follow up as soon as I get more info.

  13. #13
    Join Date
    Nov 2007
    Location
    Mississippi
    Posts
    1,274
    Oh, cycling on high psi not compressor overload.

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