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  1. #1

    a-coil wont get cold enough

    got a 12yr old lennox split system 2 1/2 ton. A-coil will only get half way cold. A-coil is clean, recovered freon, replaced liquid line dryer, removed, cleaned and check orfice, flushed out with nitrogen, pumped unit down to 300 microns and recharged with r-22. pressures are perfect, about 80 low and 225 high but no matter how much more freon i put in the pressures keep going up but the line set temp wont come down, stuck at about 80 degs. also when charging the unit, the low side needle goes in to retard like normal but when i close my gauges the needle very, very slowly goes back up. its about 85-90 degs here and im out of ideas. it was running about 325 on high side before i replaced the dryer and was causing the compressor to over heat and shut off but still the a-coil will not flood with freon and will only give me a 10 deg temp drop across the coil. any help would be appreciated dont know what else to check for.

  2. #2
    Join Date
    Dec 2002
    Location
    SouthEast NC ICW & Piedmont Foothills
    Posts
    7,635
    which half gets cold????

    might want to try another set of gauges.

    how does psi go above retard?
    It`s better to be silent and thought the fool; than speak and remove all doubt.

  3. #3
    Join Date
    Sep 2010
    Location
    Western, MO
    Posts
    871
    What tells you when you have perfect pressure? <pressures are perfect, about 80 low and 225 high>

    Is there a chart for that?

    jim
    Common sense isn't very common anymore.

  4. #4
    Join Date
    Sep 2008
    Location
    Western PA
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    25,758

  5. #5
    Join Date
    Apr 2012
    Location
    Paper Street Soap Company
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    2,304
    More gas is the panacea for all HVAC issues.......

    or is it ?

  6. #6
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,758
    Now, I'll be serious for a bit.

    You've provided a bit of information but, since you're asking for help, you've got to do a little better.

    Let's have some more data.

    Airflow, actual air on and air off temps with wetbulb, actual line temps would be a good start.

  7. #7
    Join Date
    Oct 2003
    Location
    tidewater, va
    Posts
    2,144
    what is the return wet bulb temp, may have a high humidity load on the coil


    404

  8. #8
    im saying my pressures are in range of where they should be for a 90 deg day. they are not indicating a problem but the line set temp is stuck at 80degs which is not in range and i said the needle goes into retard when charging a r-22 unit with r-22 gauges not pass retard but when you close your valve the needle should quickly go back up not take 3mins to go back up ( i replaced the valve core as well). the unit is 12 yrs old and is just now having a problem, its not a airflow problem and it doesn't matter how much more freon i put in, the pressures will keep going up like normal but the line set temp will not budge. After i replaced the liquid line dryer and got my head pressure down the compressor doesn't overheat anymore and has been running for 3 days but still the evap only gets cold and sweats on the bottom of the coil, its completely dry on the top half. It doesn't matter what my cfm, wetbulb or temps are, the coil should be saturated top to bottom. for some reason the freon is just not flooding the coil. Im leaning toward a compressor problem.

  9. #9
    Join Date
    Nov 2009
    Location
    Northwest Illinois
    Posts
    277
    Sounds like to much air across the coil, can't tell without more data.

  10. #10
    Join Date
    Apr 2004
    Location
    NJ
    Posts
    155
    Is the house very warm inside? Is there a panel open on the air handler? At 80 psig on the low side, you would have a coil temp of close to 50 degrees.
    You specified that the a-coil is clean; how about the condenser? Assuming a 12 year old condenser is likely somewhat dirty, on a 90 degree day, 225 psig would be a little low, which combined with 80 on the low side (a little high) WOULD point to leaking compressor valves probably caused by - you guessed it - overcharge.

  11. #11
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,758
    Quote Originally Posted by ultitech View Post
    It doesn't matter what my cfm, wetbulb or temps are, the coil should be saturated top to bottom. for some reason the freon is just not flooding the coil. Im leaning toward a compressor problem.
    You're wrong about that.

  12. #12
    Join Date
    Jun 2012
    Location
    Pensacola Florida
    Posts
    49
    A compressor isnt going to change a thing but the amount of the repair. Are you sure you have the right size piston for that system. Without measuring airflow, wet bulb inlet temp diff across coil. What else can i tell you?

  13. #13
    Join Date
    Dec 2002
    Location
    SouthEast NC ICW & Piedmont Foothills
    Posts
    7,635
    well, if all the other information doesn't matter enlighten us as to why.

    i'm all up to figuring out how to work smarted than harder
    It`s better to be silent and thought the fool; than speak and remove all doubt.

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