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  1. #1
    Join Date
    Dec 2007
    Location
    sevierville TN.
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    177
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    Power head causing flooding

    I ran into somthing today I have never seen in my 30 years of refrigeration. I went to a supermarket for routine checks, mgr met me in back room and asked if I could find out why all the oil failures on rack c. He said he had been resetting all four compressors several times per day for three days and the compressors were white with frost, I could not believe what I saw even the oil pumps were white. I shut off liquide line to pump down rack and clear off frost and check compressors, I then turned on each system one at a time and two separate systems were flooding. I then pulled cases two on each system to find problem, one valve on each flooding to the point of iceing suction line[ produce cases ] 1 1/2 ton G body valves 404A, closed valves did not help, pumped down both systems took valves apart could find no problems, restsrted , still same problem , replaced both power heads adjusted to 8deg. superheat all ok so far. Has anyone ever seen a power head cause a valve to flood by not allowing valve to close? These cases were installed new 2 years ago and have not been touched berore today, needless to say this was areal head scratcher. NEVER BORING IN MARKET WORK.

  2. #2
    Join Date
    Sep 2005
    Location
    florida
    Posts
    5,530
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    Nope never seen a power head fail open they fail shut txv will not feed
    with a bad power head.were the push rods stuck in the down position?
    thats the only way I could see that it could cause the system to flood
    back or the txv was just hainging upsome how. I think you have a bad
    txv you would be better off to replace it.
    I love the smell of phosgene first thing in the morning:

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  3. #3
    Join Date
    Nov 2005
    Posts
    386
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    I agree. the push rods could be the only other cause for flooding. thats forsure a good head scratcher. probally free'd them up somehow while taking the heads off. might last forever who knows

  4. #4
    Join Date
    Feb 2007
    Location
    Northern NJ
    Posts
    828
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    i also agree, bad power heads will not cause flooding, as they are the opening force of the valve. if they failed, txvs would slam shut. like said before, pushrods may have been stuck, and you freed them removing powerheads. replace the valves.

  5. #5
    Join Date
    Dec 2007
    Location
    sevierville TN.
    Posts
    177
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    Thread Starter
    Every thing was clean push rods free I could find no reason for the flooding. I dont believe in replacing parts with out knowing what the real problem is. TXV's get the blame for a lot of system problems because of a lack of knowledge. If the mfg. had real customer support everyone could be better at there job's but they seem to promote parts changing. Replacing the power heads does not make sense to me and I will find an explanation.

  6. #6
    Join Date
    Aug 2002
    Location
    Orange County CA
    Posts
    1,084
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    Has anyone recently changed LPRV setting lately?

    (LPRV=Liquid Pres Reg Valve)

  7. #7
    Join Date
    Jun 2005
    Location
    Las Vegas NV
    Posts
    1,234
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    Dang Sodd,

    That's a wierd situation. Maybe there was some sort of debris stuck in the ports that dislodged when you worked on the valves. How about moisture or ice?

    Extremely high sub-cooling would also cause the valves to overfeed but that problem wouldn't have gone away with a power head change.

    Let us know what you find.

  8. #8
    Join Date
    May 2007
    Location
    Ohio
    Posts
    89
    Post Likes
    did you cut the cap tube to the bulb and get the hisser out of it. As i understand elements they contain a charge warm it up it applies more downward force on the needle to open the valve cool it down it contracts closing the valve so if you dont have any gas in the element how is it going to apply downward force on the dome to open the valve.

  9. #9
    Join Date
    May 2000
    Location
    Monmouth Junction-NJ-USA
    Posts
    6,122
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    When you lose the "Hisser", it pumps down.
    If you really know how it works, you have an execellent chance of fixin' er up!

    Tomorrow is promised to no one...

  10. #10
    Join Date
    May 2007
    Location
    Ohio
    Posts
    89
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    ok if the spring force overcomes the dome force what happens because you got three pressures acting in unison and against one another.

  11. #11
    Join Date
    Nov 2004
    Location
    Anchorage Alaska / Seattle WA
    Posts
    205
    Post Likes

    Tweakers

    Never overlook a tweaker. An adjustable wrench a small amount of knowledge and a large amount of curiosity (usually a kid) could cause a seriously out of whack TXV in some random fashion like you describe. Or a fairly smart disgruntled employee either way can give a service man a perplexing headache.

  12. #12
    Join Date
    May 2007
    Location
    Ohio
    Posts
    89
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    what a dumb@$$ I am of course the closing force of the spring will close the valve if the element fails sorry dudes got dyslexia on the brain thinking in reverse.

  13. #13
    Join Date
    May 2000
    Location
    Monmouth Junction-NJ-USA
    Posts
    6,122
    Post Likes
    Quote Originally Posted by jonny in La View Post
    what a dumb@$$ I am of course the closing force of the spring will close the valve if the element fails sorry dudes got dyslexia on the brain thinking in reverse.
    /

    Knew you would figure it out!!!
    If you really know how it works, you have an execellent chance of fixin' er up!

    Tomorrow is promised to no one...

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