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Thread: TXV

  1. #1
    Join Date
    Jul 2009

    Question TXV

    Had a txv issue would like to hear from the more experienced. Went back on an install. Installed in Aug/12- 2 ton heat pump with a/h on a townhouse both at ground level (walk out basement) up flow. Liquid line freezing up after the piston at the service valve including line up to distributer and lines going into condenser coil. Thought it was a clogged piston but turned out to be the indoor Txv. Ran nitrogen thru suction port and disconnected liquid line after pump down and nitrogen pressure seemed fine coming out liquid line. System worked fine in a/c had gauges on pressures good and subcool was around 6 but not much of a load on home. Switched to heat and both liq/suc would pump down untill unit would go out on L/p. Checked piston and was right size and replaced liquid line dryer and weighed in 410a charge after opening up system and thats when it did the same thing. Why wouldn't I see frosting at the Txv, but yet 50 feet down the line it is freezing up on the other side of the piston? I'm sure the installers never tested it in heat in aug. Thanks

  2. #2
    Join Date
    May 2009
    Cummins, GA
    This post is little confusing. Please post make, model, and serial.

    I assume it is heat pump. An indoor TXV bypasses in the heat mode.

    You talk about a piston and TXV. Does it have a TXV @ the evaporator and a piston @ the condenser? Was the original problem in cooling or heating? Clarify some things and I am sure you will receive more responses.

  3. #3
    Join Date
    Mar 2011
    North Carolina Piedmont Area
    You have a TXV at the evaporator....I get that part, but where is that piston at? Are you referring to a check valve at the outdoor unit?

    A model number would really help.

  4. #4
    Join Date
    Jul 2009
    Columbia, MD
    sounds like a rheem or something. charge is good in a/c but when switch to heat it looks low. check the piston at the outdoor unit. make sure its installed in the correct orientation and not restricted. also allow 15 mins of runtime to equalize. maybe try pushing in contactor and watching unit run but dont let it go into a vacuum

  5. #5
    Join Date
    Feb 2009
    Tallahassee, FL
    Sounds like a carrier to me.

    Its frosting because its below frost point after piston. Really not abnormal if oda drops

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