High liquid line pressure
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  1. #1

    High liquid line pressure

    I have a system I just installed 3 to 14 seer 410a
    ac with a 5 ton evap. coil , txv, on a furnace with a 4 to drive.
    pulled a good vacuum, and let 410a into the system.
    suction side is at 150 psi, and the liquid lie pressure is bouncing between 375-550psi.
    what the heck is going on???
    any suggestions will be appreciated.
    Thanks,
    Chris

  2. #2
    Join Date
    Aug 2007
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    Winter Haven, FL
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    4,228

    high liquid line pressure

    Non condensibles

  3. #3
    Join Date
    Mar 2011
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    254
    Why is this post in the job discussion forum?

  4. #4
    Join Date
    Jun 2012
    Location
    Great lakes
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    Did you charge the system with more freon, generally a new condenser only comes factory charged with enough freon for a15 foot line set. And if you did what was your super heat and sub cooling. Under charged system with a txv valve will give you some weird pressures.

  5. #5
    Join Date
    Sep 2010
    Location
    Western, MO
    Posts
    871
    Is that a 3 ton condenser with a 5 ton coil and a four ton furnace?

    It must be my confused night.

    jim
    Common sense isn't very common anymore.

  6. #6
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    Threads merged, please don't make duplicate threads, thank you.
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    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  7. #7
    Join Date
    Oct 2011
    Location
    Springfield, Missouri
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    18
    So in cooling is the reversing valve energized did you wire correctly. If so is txv receiving liquid or is it being bombarded with gas pockets (undercharge). Was it a new line set or was old set used and what sizes are the line sets? 410 is very very temperamental air flow must be correct and system must be correctly sized for application. You may be low on freon or gas pockets in the system that is slamming against the needle of the txv and that may be your violent swings in pressure

  8. #8
    Join Date
    Jul 2010
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    nebraska
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    What's a good vacuum? Used a micron gauge or just let the pump run for a long time? If you pulled to under 500 microns and it held there with the pump off we should be able to eliminate noncondensables as the problem. If you didn't use a micron gauge then Joe is probably right.

  9. #9
    Join Date
    Oct 2010
    Location
    Calgary, Alberta
    Posts
    17
    Quote Originally Posted by martyinlincoln View Post
    What's a good vacuum? Used a micron gauge or just let the pump run for a long time? If you pulled to under 500 microns and it held there with the pump off we should be able to eliminate noncondensables as the problem. If you didn't use a micron gauge then Joe is probably right.
    Yup, seen that a few times. Might have to recover, evac and recharge to rule it out for sure. Whats your comp discharge temp?

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