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Txv

townsquarehvac
townsquarehvac Member Posts: 6
in A-C, Heat Pumps & Refrigeration
Recently at the shopping center I work at, I had a couple of txv's that i believe are malfuntioning.  They are non bleed txv's, and are passing absolutely no refrigerant through the valve. I hate to make a diagnosis based on supposition and guessing.  Is this a normal failure or am I not understanding how these things work?  Is there maybe something else i can look at? It seems like no matter how mucgh refrigerant I put into this thing, the compressor always pulls the suction side into a vaccuum. Thanks for your help!!!

Comments

  • Techman
    Techman Member Posts: 2,144
    TXV

    Could be! What size TXV are these? It might be the Power Assembly. Turn the superheat stem all the way out,and it might bleed some freon thru. Wrap a hot towel around the TXV thermal bulb and you might get some freon to leak thru.
  • JStar
    JStar Member Posts: 2,752
    edited September 2011
    More numbers.

    If it's pulling into a vacuum, I'd suspect a total restriction, in either the TXV or a filter/drier.
  • townsquarehvac
    townsquarehvac Member Posts: 6
    txv

    Ok, so I wrapped a hot towel around the txv bulb and got nothing.  I had to back the superheat stem almost all the way out before I got any bleed through, but there was charge coming out of the stem.  I'm going to go with a bad diaphragm in the txv.  Or possibly a pinhole leak in the bulb cap tube.  Either way, I'm going to replace the txv.
  • Techman
    Techman Member Posts: 2,144
    TXV

    It's not supposed to leak thru the superheat stem packing/seal.What size TXV /system ?
  • townsquarehvac
    townsquarehvac Member Posts: 6
    txv

    Its just a 2ton unit.  Not sure about the size of the txv. 
  • John Mills_5
    John Mills_5 Member Posts: 952
    Typical

    Common failure on a little TXV. Probalby not adjustable. Have to replace it. Hopefully it is a bolt on!
  • Eugene_Silberstein
    Eugene_Silberstein Member Posts: 349
    Opening pressure on the TXV

    There are three pressure that control the operation of the TXV: The bulb pressure, the spring pressure and the evaporator pressure.



    If the valve is closed and not passing any refrigerant, than there is no opening pressure, indicating that the charge in the thermal bulb (powerhead assembly) has been lost.



    Pretty much an open-and-shut (no pun intended) case.



    Good luck!

    There was an error rendering this rich post.

  • townsquarehvac
    townsquarehvac Member Posts: 6
    txv

    Thanks Eugene.  It's funnny that you mention that, when I went to replace the txv, I noticed that there was a spot on the cap tube for the bulb that had been rubbing on a refrigerant line that had rubbed all the way through. Thanks everyone for all your input.  I think this is a sight I will use in the future for help when i get stumped.
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