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  1. #1
    Join Date
    May 2016
    Posts
    2
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    Increased orifice size - suction line pressure went DOWN!

    It's a Lennox HS29A-043 4-ton R-22 unit.

    Got it second hand to replace a bad unit. Cools okay but subcooling is 12 deg too high, Suction line pressure 20 lbs. too low. 'Mkay.

    Recovered a pound and a half of R-22 to be on the safe side. Pumped it down. Pulled orifice, found .081. replaced with .086 per the book.

    Leak check - pulled vacuum. Suction line now 20 lbs. LOWER than before! Like 30 psi. A larger orifice should give a higher suction pressure, not a lower one. Put the recovered R-22 back in. Pressure now back up to where it was before. Subcooling close to normal now.

    What gives? This unit seems to behave backwards from what it's supposed to.

    Still cools okay but when the temp gets up to 106 every day here, I'm gonna have a frozen up evaporator with this pressure.

  2. #2
    Join Date
    Mar 2009
    Location
    Mount Holly, NC
    Posts
    6,012
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    This forum isn't for technical discussion.
    The TRUE highest cost system is the system not installed properly...

    Find a HVAC-Talk Contractor by clicking here

    Do you go to a boat repairman with a sinking boat, and tell him to put in a bigger motor when he tells you to fix the holes?

    I am yourmrfixit

  3. #3
    Join Date
    Jan 2008
    Posts
    2,744
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    Installing used equipment was your first mis-step.
    And I think that is a 3.5 ton unit, not 4 tons.
    "Hey Lama, hey, how about a little something, you know, for the effort." And he says, "there won't be any money, but when you die, on your deathbed, you will receive total consciousness." So I got that goin' for me, which is nice. - Carl Spackler

  4. #4
    Join Date
    Feb 2010
    Location
    Calgary, Alberta
    Posts
    1,634
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    Lol, OOPS

    No offence man, but you need to hit the books before touching another system.


    Sent from my iPhone using Tapatalk

  5. #5
    Join Date
    May 2016
    Posts
    2
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    Quote Originally Posted by 2old2rock View Post
    Installing used equipment was your first mis-step.
    And I think that is a 3.5 ton unit, not 4 tons.
    1. It's a 4 ton unit.
    2. FYI they don't make R-22 units new any more.

  6. #6
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    6,385
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    Typical low airflow issue also 12 degrees subcool does not mean much in a piston metering device .is the coil clean and what happened to the other unit
    Stuff happens

  7. #7
    Join Date
    Jul 2010
    Location
    nebraska
    Posts
    2,186
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    Dave net didn't show that model number for current or out of production units. Closest is a HS29-042 which is a 3.5 ton unit. Measure your air flow first then check superheat.

  8. #8
    Join Date
    Aug 2012
    Posts
    3,375
    Post Likes
    Did you change the filter drier?

  9. #9
    Join Date
    May 2016
    Location
    Australia
    Posts
    45
    Post Likes
    What is the suction pressure now? 20-30psi could mean a whole range of different issues. Airflow, system charge, restriction.

  10. #10
    Join Date
    May 2005
    Location
    South
    Posts
    735
    Post Likes
    Have a picture of that model number. I say HS29A-043 doesn't exist.

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