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Thread: Head pressure

  1. #1
    Join Date
    Jun 2005
    Location
    WNY
    Posts
    18

    Hmm

    I fired up the 10 ton carrier unit Ive been working on. the problem is it is a split condensor 5T and 5T identical line sets to the coil one side is running fine, but the other has high head pressure with low suction pressure. this unit is 1yr old. and I did as always install new filters and sight glasses. I also cleaned the condensor as I always do before starting the unit. what else am I missing?

  2. #2
    Join Date
    Dec 2002
    Posts
    9,871

    TXV or Fixed orifice?

    Could be restriction with overcharge plus noncondensibles!!

  3. #3
    Join Date
    Jun 2005
    Location
    WNY
    Posts
    18
    IT can't be an overcharge, same exact amount went into both sides. It took 1hr. to get to 500 microns, wich I pulled for an additional 1/2 hr. let it sit in vaccum for a 1/2 then charged. some type of blockage comes to mind but what?

  4. #4
    Join Date
    Jun 2005
    Location
    WNY
    Posts
    18
    Oh I forgot to mention TXV

  5. #5
    Join Date
    May 2004
    Posts
    12,028
    If it was a restriction the head and suction would both be low and your superheat and subcooling and discharge temperature high.

    Give us the model # and are these scroll's and 3 phase?

  6. #6
    Join Date
    Dec 2002
    Posts
    9,871

    We could help you better

    If you provide pressures, superheat, and subcool.

  7. #7
    Join Date
    May 2004
    Posts
    12,028
    Rob, ya think he has a scroll backwards?

  8. #8
    Join Date
    Jun 2005
    Location
    WNY
    Posts
    18
    Notebook is in the work van. I'll get back to you monday with the pressure, super and sub. I actually wrote the model number down this time(I usually don't bother in my notes,and it comes back to haunt me!)

  9. #9
    Join Date
    Dec 2002
    Posts
    9,871

    Possible I suppose

    Originally posted by lusker
    Rob, ya think he has a scroll backwards?
    But the scrolls I've seen running backwards have always had equalized pressures. Being a split condenser, I would guess he did not get it as clean as he thinks for the head pressure problem. The txv bulb may be on the bottom of the suction giving it lo pressure. Strictly guessing right now.

    [Edited by rob10 on 06-11-2005 at 08:50 PM]

  10. #10
    Join Date
    May 2004
    Posts
    12,028
    Carrier 10T are not TXV they are acculators (sp?) fixed metering. This thing sounds like a 48TJD012. If it is the high head could be coming from a restriction in the new condenser coil or a factory strainer.

  11. #11
    Join Date
    Jun 2005
    Location
    WNY
    Posts
    18
    Just the condensors are carrier, the air handelers with the coil are unknown. they date 1984 but all other markings are gone. the coil is a split with twin external TXV's

  12. #12
    Join Date
    May 2004
    Posts
    12,028
    come on man.. got to make my day here somewhere!

  13. #13
    Join Date
    Jun 2005
    Location
    WNY
    Posts
    18
    I got pulled off that job, they sent in my senior tech and his outcome was the TXV. he said the tube and bulb were bad. being new to this field, I really wanted to fix the problem. I vissually inspected both TXV's, tubes and bulbs. I saw nothing wrong, no freezing, not pinched, nothing. What did I miss? maybe I just need experience!

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