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Thread: High pressure

  1. #1
    Join Date
    Mar 2012
    Location
    Raleigh, NC
    Posts
    34

    High pressure

    Hey guys,
    I asked this question earlier but didn't really get an answer yet. I replaced an evaporator coil on a 3.5 ton carrier unit with a goodman coil, because the existing coil was rusted and leaking beyond repair. It came with a piston valve but after trying a couple different size pistons and still having high pressure, 320 psig, I switch to a txv. The pressure dropped a little bit, about 295, but I am still not able to get proper subcool temps. Also the pressure is still way high considering it's only 75 degrees, outside temp. I was only able to get 88 degrees or so on the high pressure side which means the subcool is way off. The superheat is within 15 degrees but I know with a txv subcool is what is important. Other than a restriction in the line, is there another possible cause? Of course I changed out the line drier when I installed the txv.

  2. #2
    Join Date
    Feb 2010
    Location
    In a boiler room
    Posts
    7,142
    Did you evacuate? What Micron level did you achieve?

    It looks like you have over 40 SC. Start taking out Refrigerant until you get down to a more realistic SC.

    R22?

  3. #3
    Join Date
    Mar 2012
    Location
    Raleigh, NC
    Posts
    34
    sub cool was 42. outside temp was 75

  4. #4
    Join Date
    Feb 2010
    Location
    In a boiler room
    Posts
    7,142
    Quote Originally Posted by Cool Change View Post
    sub cool was 42. outside temp was 75
    It's way overcharged.

  5. #5
    Join Date
    Mar 2012
    Location
    Raleigh, NC
    Posts
    34
    I will try that. yes, I evacuated, but had to do it the old fashioned way cause my micron gauge quite working and I am waiting for johnstone to get it back from the manufacturer. By the old fashioned way I mean vacuumed for 45 minutes, turned it off, waited fifteen and did it again. repeated

  6. #6
    Join Date
    Mar 2012
    Location
    Raleigh, NC
    Posts
    34
    thanks for the feed back chuck crj

  7. #7
    Join Date
    Mar 2012
    Location
    Raleigh, NC
    Posts
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    and yes, it is r22

  8. #8
    Join Date
    Jun 2011
    Location
    sfv california
    Posts
    108
    way overcharged txv is prob wide open and your just raising pressure was this at your house or customers

  9. #9
    Join Date
    May 2008
    Location
    Myrtle Creek. Oregon
    Posts
    182
    is the condensor clean? just a thuought.
    a stupid question is a question you wont to ask, but don't

  10. #10
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,676
    Quote Originally Posted by cboe View Post
    is the condensor clean? just a thuought.
    Ill bet not

  11. #11
    Join Date
    Mar 2012
    Location
    Raleigh, NC
    Posts
    34
    yes, the coil is clean. And Honestly I cant see y I would be overcharged. The factory charge is 5.4 pounds, plus a half ounce for every foot of line-set after 15 foot. 80 foot of line-set. That's 32.5 ounces. I know I started checking my subcool temps when I reached 6 pounds...

  12. #12
    Join Date
    Apr 2009
    Location
    Pan Handle, Fl
    Posts
    600
    Whats line set size? Need to charge with sc with txv. Bring it down to 10 and see what happens. Sounds like your over charged. Of course check the air flow and get it right.
    Insanity: Doing the same thing over and over again expecting a different outcome!

  13. #13
    Join Date
    Jul 2009
    Location
    South Carolina
    Posts
    3,245
    You said SH was around 15 but what was your suction pressure?
    Gary
    -----------
    http://www.oceanhvac.com
    An engineer designs what he would never work on.
    A technician works on what he would never design.

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