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  1. #1
    Join Date
    Feb 2010
    Location
    New York City
    Posts
    74

    External Equalizer Line Ices Up

    10 Ton Scroll Compressor, R-22 AIR Conditioner
    Suction: 51 P.S.I. Discharge: 200 P.S.I.
    Condenser water in :75 Degrees
    Air Temp entering evap coil :74 Deg
    Evap Coil Clean, good air flow across coil
    14 Degree :split air across evap coil ( This delta T is normal for these units)
    New Power head on expansion valve
    I throttled down on the TXV
    Superheat measured at suction line feeler bulb : 20 Degrees
    I may be overcharged. The suction line and half compressor are really sweating back
    There is good amount of foam in the oil sight glass
    I gather there is liquid boiling off in the External Equal. Line
    Why would the suction pressure be so low?

  2. #2
    Join Date
    Nov 2004
    Location
    up in the hizzy
    Posts
    1,440
    whats the leaving water temp? at 51psi the evap must be iced up, your measurement are kind of screwy

  3. #3
    Join Date
    Jun 2008
    Location
    Windsor, Ont.
    Posts
    516
    It seems to me that you have liquid refrigerant flowing through your equalizing line which is giving your TX valve a false evaporator pressure. I'd start with a new TX valve, JMHO.

  4. #4
    Join Date
    Sep 2002
    Posts
    2,890
    That sounds like an internal leak in the valve,was it doing that before you changed the power head?

  5. #5
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,946
    Quote Originally Posted by nyrb View Post
    It seems to me that you have liquid refrigerant flowing through your equalizing line which is giving your TX valve a false evaporator pressure. I'd start with a new TX valve, JMHO.

  6. #6
    Join Date
    Jan 2010
    Posts
    6,829
    What about a restriction in that equalizer line

  7. #7
    Join Date
    Oct 2009
    Location
    God's country - Shenandoah Valley, VA
    Posts
    403
    Quote Originally Posted by techservices View Post
    The suction line and half compressor are really sweating back
    There is good amount of foam in the oil sight glass
    I gather there is liquid boiling off in the External Equal. Line
    Why would the suction pressure be so low?
    Liquid is leaking past the O rings on the lift rods. There should be NO liquid in the equalizer line.

    Replace or rebuild the valve (if that's possible).

  8. #8
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,789
    Quote Originally Posted by bobboan View Post
    Liquid is leaking past the O rings on the lift rods. There should be NO liquid in the equalizer line.

    Replace or rebuild the valve (if that's possible).
    Yep.
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  9. #9
    Join Date
    Sep 2002
    Posts
    2,890
    I have seen where the leak at the pushrods is small,just enough to hit the power head and back the valve off.

  10. #10
    Join Date
    Jun 2011
    Location
    Houston area
    Posts
    1,493
    Quote Originally Posted by bobboan View Post
    Liquid is leaking past the O rings on the lift rods. There should be NO liquid in the equalizer line.

    Replace or rebuild the valve (if that's possible).
    Yep, only gas. I would second that the TXV is suspect.
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  11. #11
    Join Date
    May 2003
    Location
    Utah
    Posts
    743
    Quote Originally Posted by bobboan View Post
    Liquid is leaking past the O rings on the lift rods. There should be NO liquid in the equalizer line.

    Replace or rebuild the valve (if that's possible).
    Rebuilding the valve will typically not solve this problem. Most TEVs do not have packings to provide the seal between the pushrods and pushrods hole...there are a few exceptions. The seal is a function of the clearance between the pushrod diameter and the pushrod hole diameter. If the clearance between the two is excessive you will have leakage.

    Since all machined parts have a +/- tolerance, there is no telling if the pushrods contained in the parts kit will actually be of a diameter which will prevent the leakage.

    Additionally, if a valve is rebuilt, the pushrods will need to be filed down to the proper length (by measuring the pushrod height above the top of the valve, using a pushrod gauge). All pushrods in parts kits are purposefully too long...neglecting to file them down will increase the valve stroke, causing a capacity increase.

    Replace the valve.

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