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  1. #14
    Join Date
    Feb 2009
    Location
    Wisconsin
    Posts
    311
    Pump it down and clean the TXV screen.
    You have to fight through some bad days to earn the best days of your life.

  2. #15
    Join Date
    Feb 2006
    Location
    USA
    Posts
    4,381
    Quote Originally Posted by thermofridge View Post
    Pump it down and clean the TXV screen.
    i would hope it's not full of trash that fast lol

  3. #16
    Join Date
    Feb 2008
    Location
    California
    Posts
    2,066
    whats your

    SCT at?

    SST at?

    Are you maintaining a solid column of liquid?

  4. #17
    Join Date
    Mar 2007
    Location
    pittsburgh, pa
    Posts
    536
    Have you checked to see if a coil or pan heater is energized?

  5. #18
    Join Date
    Mar 2007
    Location
    NW AR
    Posts
    2,478
    cracker: it came with 4 orifices. two for r-22 and two for the various other reefers. the correct one was field installed

    crymtide: its at 10 oclock and is horizontal. my bad there, the book shows 4 or 8 or 3 or 9 oclock. ill move it this morning after confirming its working. yes its insulated.

    hvac and thermo: ill be checking the screen today. hard to believe i got trash in it since we bubbled n2 while brazing

    phase: it was cool yesterday. sct was around 100 sst was -20 with a line temp of +5 deg. full column to the txv.

    76: 0 amp draw from all heaters

  6. #19
    Join Date
    Jul 2000
    Location
    Guayaquil EC
    Posts
    10,328
    Quote Originally Posted by crackertech View Post
    Just a thought I once had coil we ordered fore R-22 but it was shipped with a 404 orifice in it drove us crazy.
    This is a good point. The distributor nozzle sizing for R22 and R404A are vastly different.

    The OP has stated that he has the correct one in there, but I've found in a few cases, the nozzle size was a tad small for the application...especially for freezer pulldown.

    Heatcraft's Refigeration Systems I&O manual has a good section of nozzle sizing (starting on p.7):
    http://www.heatcraftrpd.com/products...5CH-IM-64L.pdf

    I would also recommend going up one size on the Q-Valve orifice, to a QC-4. The FJAL-B301 has a capacity of 9470 Btuh at -20F SST/90F Ambient but it's 13,100 at -10F SST/90F. The system seems to match up OK for the -20F condition, but it's clear the TXV will be undersized for pulldown.

  7. #20
    Join Date
    Mar 2007
    Location
    NW AR
    Posts
    2,478
    Thanks all Im off to the races Ill let you know what I find.

  8. #21
    Join Date
    May 2004
    Posts
    11,999

  9. #22
    Join Date
    Jul 2000
    Location
    Guayaquil EC
    Posts
    10,328
    Quote Originally Posted by Dad View Post
    My money is on the power head being bad. Doubt it is a MOP valve but that could also explain why adjusting doesn't give him movement.
    The possibility of MOP powerhead did come to to mind. There's no adjusting those if the suction pressure is above 30#-35#. It was stated however, that it's a KT43-SZ, which is the non-MOP, standard powerhead, so I think we can rule that out.

    The existing head may well be bad, but if it were, I would expect the valve to slam shut.

    Another possible problem, now that the TXV has been cranked every whichaway, is that the adjustment stem has been FUBAR'd...in which case a new valve would be needed.

  10. #23
    Join Date
    May 2004
    Posts
    11,999
    Quote Originally Posted by icemeister View Post
    The possibility of MOP powerhead did come to to mind. There's no adjusting those if the suction pressure is above 30#-35#. It was stated however, that it's a KT43-SZ, which is the non-MOP, standard powerhead, so I think we can rule that out.

    The existing head may well be bad, but if it were, I would expect the valve to slam shut.

    Another possible problem, now that the TXV has been cranked every whichaway, is that the adjustment stem has been FUBAR'd...in which case a new valve would be needed.
    Yeah.. I saw the #'s on the valve while I was blitzing through this.

    The head may not have totally leaked down, just the wrong charge pressure on it... want to see my box of old power heads?

    Not to hijack but found this at a shiny brand new cooler install that went to the lowest bidder... that means we didn't get the bid but were asked to go back and fix it.... cheap aftermarket line set on both cooler and freezer, excess coiled up and left on top of the boxes (over 20' of access). 3/8 insulation instead of the factory 1" they require which was also sent by the factory with the proper length of line set... both boxes leaking water everywhere and temps were bad... SH in the freezer was 13, cooler wouldn't cool at all... You know those stories all too well.

    See the pic? Installer took a torch to the body thinking it was internally iced. He couldn't understand why the valve wouldn't adjust. After we found the liquid side areoquip fitting at the condenser wasn't fully engaged/pierced this valve wouldn't adjust... don't know why.. HA
    Attached Images Attached Images  

  11. #24
    Join Date
    Mar 2007
    Location
    NW AR
    Posts
    2,478
    Showed up to a -10 degree box yesterday. Stem at midpoint, still 25 deg sh. Pulled bulb and warmed it. Suction rose and suction line temp plummeted.

    Screen had zero debris in it.

    Reattached bulb and insulated. One turn away from being fully open and cannot get superheat down. Im stumped

    Ive got a new txv but would like to know if you think I should stick a #4 in it before pulling and replacing?

    Also..what damage can be done by adjusting the stem?

  12. #25
    Join Date
    Sep 2005
    Location
    florida
    Posts
    5,506
    Quote Originally Posted by ar_hvac_man View Post
    Showed up to a -10 degree box yesterday. Stem at midpoint, still 25 deg sh. Pulled bulb and warmed it. Suction rose and suction line temp plummeted.

    Screen had zero debris in it.

    Reattached bulb and insulated. One turn away from being fully open and cannot get superheat down. Im stumped

    Ive got a new txv but would like to know if you think I should stick a #4 in it before pulling and replacing?

    Also..what damage can be done by adjusting the stem?


    None unless you went past the stop.
    I would put a #4 in it first.
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  13. #26
    Join Date
    Jul 2000
    Location
    Guayaquil EC
    Posts
    10,328
    The fact that you got a huge surge of flow when the bulb was warmed up tends to lead me agree with what Dad was saying about the powerhead losing its charge.

    Since you have to remove the powerhead to replace the orifice, I'd go ahead and replace the powerhead as well.

    Then again, you may want to do the powerhead first, just to determine if it was indeed the problem all along.

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