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  1. #1
    Join Date
    Sep 2002
    Location
    Virginia
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    So I went with 407C

    3 ton straight AC

    2nd and 3rd floor unit

    Goodman unit with the little ass dryer inside the compressor section was totally plugged up so bad the line was cold , so I remove that and put the dryer on the outside of the unit

    Gave it about 80 percent charge and im lost on the temps to watch for because ive never had a house 90 deg inside

    So high side is 210 , low 83 SH is 25

    Has a piston

    Outside temp 82

    I thought maybe the compressor was weak so I shut the liquid line off and both sides pulled down to 10 psi easily

    This thing gonna live with that high suction ?

    What SH should i look for with those conditions

  2. #2
    Join Date
    Sep 2018
    Location
    Mojave Desert California
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    54
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    Superheat with a piston is relative to the load and you can’t calculate it without indoor wet bulb. Pressures will change after load decreases ie: indoor temperature decreases

  3. #3
    Join Date
    Sep 2002
    Location
    Virginia
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    Thread Starter
    I called my buddy Beshvac , and he said add some, so i added and now have 88 suction , line temp 63 , so thats what , 14 SH ...roughly

  4. #4
    Join Date
    Apr 2003
    Location
    Maple Grove, MN
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    I think you were closer the first time. I would be worried that as the thing catches up and the load drops, the superheat will drop too.

    Are you measuring superheat near the evaporator or right before the compressor? If it's right by the compressor then you're definitely too low. If I remember correctly, superheat at the compressor should be a minimum of about 20 degrees.

    Either way I think I'd remove a little bit of the reefer.
    If at First You Don't Succeed, Skydiving Is Not for You.

  5. #5
    Join Date
    Sep 2002
    Location
    Virginia
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    Thread Starter
    Thats at the condenser

  6. #6
    Join Date
    Feb 2006
    Location
    Float'N Vally, MS
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    2,763
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    Quote Originally Posted by Snapperhead View Post
    Thats at the condenser
    Go have a beer...
    Let it pull down, about sunset, and check again.
    You may be close where you are at.... It's a (older) Goooman....
    Life is too short, Behappy!
    TFMM

  7. #7
    Join Date
    Dec 2014
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    2,564
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    At 90 DB indoors, very likely, you'd see 95 psi SP with 407C.

    I think you may be undercharged and low airflow and if those were right, head would be 250ish.

    Sent from my SM-G950U using Tapatalk

  8. #8
    Join Date
    Sep 2005
    Location
    Atlanta GA area
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    IMO... with those conditions, assuming proper airflow inside...
    An initial (right after start-up) SH in the low 20's would be about right.

    As noted... one needs indoor WB to do accurate SH with a piston.

    If you do not have a sensor available and the app on your phone...
    Go back and check it when it cools down.

    Generally, Goodmans like to run with a more flooded coil than others... so a SH in the 10-12 should work.
    If it was any other brand, I would say 12-15 when it is more or less at temp inside.

    407C tends to have a slightly wider DT* temp... couple extra *F...
    I like it as a replacement, and it is cheaper!
    GA-HVAC-Tech

    Your comfort, Your way, Everyday!

  9. Likes CEAS-AC-TECH liked this post

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