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  1. #1
    Join Date
    Mar 2008
    Posts
    59

    Plugged piston??

    I wanted to ask (honestly) the more experienced techs on here there opinion. I am a installer with 17 yrs. experience. In the past couple of years we have gotten new service techs at our shop. They claim that flux can actually crystalize and plug the piston causing high head pressure. I think sometimes they simply dont know what is wrong with the system and use this as an excuse. I have never heard of this before and think these guys have my boss totally snowed!! If I am offbase let me know. I just want to know the truth. I cant see flux plugging the piston it doesnt make sense to me!! Thanks for the responses!!

  2. #2
    Join Date
    Mar 2004
    Location
    Grottoes VA
    Posts
    5,856
    Flux, copper shavings, dirt, rubatex powder, etc... Can cause the piston to plug up. A restriction will cause the suction pressure to drop and with no gas to compress at the compressor the head pressure will drop too.
    Karst means cave. So, I search for caves.

  3. #3
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,309
    Yes, flux can cause restrictions.
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  4. #4
    Join Date
    Mar 2007
    Location
    Connecticut
    Posts
    104
    Quote Originally Posted by karsthuntr View Post
    Flux, copper shavings, dirt, rubatex powder, etc... Can cause the piston to plug up. A restriction will cause the suction pressure to drop and with no gas to compress at the compressor the head pressure will drop too.
    Ditto...restrictions cause superheat to go up, subcooling to go up, evaporating temp (suction pressure) to drop and condensing temp (discharge pressure) to drop.

    High head is caused by non-condensibles, overcharging, and/or fouled condenser coils (or bad condenser fan ops). If your tech friend is seeing high head it is because of other skill set deficiencies, and he/she needds to read through the troubleshooting guides in the back of most installation manuals.

    With this said, we see a LOT of techs respond to low suction by adding refrigerant and flood the condensers to get the low side to respond. They create so much head that it can overcome partial restrictions, so they are happy with the measured "pressures". Always measure both Superheat and Subcooling. It takes away a lot of the guesswork, and tells you where and how much refrigerant is in the two sides of the system.

  5. #5
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,357
    Next time you find a plugged up piston, pump the system down and disassemble the piston. Then you'll begin a personal tally of what you can find in those things.

  6. #6
    Join Date
    Mar 2008
    Posts
    59
    Thankyou for the answers! I have just recentely signed on to this site and it has been great! I have learned a lot! Like I said I dont mind being wrong I just want to know the truth.

  7. #7
    Join Date
    Aug 2006
    Location
    Longview,TX.
    Posts
    83
    Don't forget the little pieces of plastic from the copper cap covers and the leetle peices of valves from the old compressor.

  8. #8
    Join Date
    Jun 2007
    Location
    Central, FL
    Posts
    871

    Yes!

    ALWAYS! Solder with nitrogen purgin threw the system, it make all the diffrence in the world. If you dont you end up with all those unwanted metering issuses.
    WARNING:IF YOU DON'T KNOW THEN DON'T DO, SO THOSE WHO KNOW WHAT YOU DIDN'T KNOW DON'T END UP UNDOING WHAT YOU DID SO IT COULD GET DONE RIGHT!

  9. #9
    Join Date
    May 2006
    Posts
    122
    I've had carbon powder plugg all 12 orrafices on a voyager unit...retro'd a txv in

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