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  1. #14
    Join Date
    Jun 2004
    Posts
    873
    Looks like you you have a duplicate post.

    Listen to
    MR bill

  2. #15
    Join Date
    Mar 2009
    Location
    Mid-Mo
    Posts
    3,596
    I also agree that a sight glass should not be used for charging in this application. If this were a refrigerator with a receiver then I'd say yes. A sight glass is there to tell you if you have moisture in the system, not as a "clear the glass and the charge is good" things.

  3. #16
    Join Date
    Aug 2012
    Location
    Tennessee
    Posts
    67
    Assuming the system (other than refrigerant cycle) is running correctly. I would say recover refrig, blow nitro just in case TXV has debris, but It sounds like replacing the drier and charging unit should fix this. Try removing the TXV bulb first and see if your power head is working

  4. #17
    Join Date
    Apr 2012
    Location
    Louisiana
    Posts
    719
    Quote Originally Posted by Cmstech View Post
    Assuming the system (other than refrigerant cycle) is running correctly. I would say recover refrig, blow nitro just in case TXV has debris, but It sounds like replacing the drier and charging unit should fix this. Try removing the TXV bulb first and see if your power head is working
    Piston #83

  5. #18
    Join Date
    Dec 2002
    Location
    Arizona
    Posts
    4,416
    At 70* IDDB and 70* ODDB you should have 10* of SH. With a matched indoor unit it calls for an #83 piston. The unit calls for 8lbs 6oz for a 15' line set ( and you added 7lbs?). You started with 200/75 and then added 7lbs ( ouch)?

    At 70* ODDB you should be around 65/190. See the Trane Fast Fact attachment.2TWA0048.pdf


    Your OVER CHARGED.
    Make your expertise uniquely valuable.

    Make your influence uniquely far-reaching.

  6. #19
    Join Date
    Apr 2012
    Location
    Louisiana
    Posts
    719
    Is it possible that there is an indoor check valve? What was outdoor temp?

  7. #20
    Join Date
    Sep 2012
    Location
    New York
    Posts
    175
    Most systems are charged by superheat so if your pressures, temp. split etc are alright dont worry about a few bubbles there has been plenty of times ive left systems with some bubbles in the sight glass. Is there a lot of bubbles? what is the size of them where in the glass are they flashing more towards the outlet? Is there a leak on the system or a history of adding gas?

  8. #21
    Join Date
    Jun 2004
    Posts
    873
    I can't believe boss man wants to keep chugging it with juice..

  9. #22
    Join Date
    Apr 2004
    Location
    Des Plaines,IL
    Posts
    1,018
    Quote Originally Posted by millertime77 View Post
    Went on this call at a church, back for leak check today, but pressures where I left them. Turned the unit on and it was 76 inside and turned down to 72. Pressures were 200/75. Coil split was 18, and sweating all the way through on all u bends. Super heat was 2 to 3 and subcool was 1 to 2, with bubbles in sight glass, but very minimal, almost milky looking. T-stat satisfied in a half an hour. Went over evap coil with leak detector and nothing. Went to outdoor unit and found a leak on top of suction service valve with cap off( not shrader portion) tightened cap up and not leaking. Found a leak on true suction service port. Seemed like someone had over tightened the shrader b/c could not get core tool on shrader, so leak locked cap. My boss says to keep throwing refer to it but that goes against the grain. Indoor piston(#83) low super heat(measured at service valve), but has low subcool, and bubbles in sight glass. Added a total of 7lbs counting both visits. I knoiw it has to be overcharged, but delta t good and RH 50% db 70 wb 60. Outdoor unit Trane M# 2TWA0048A3000AB S# 3471N213F, indoor unit is 4 ton dont have numbers though. I wonder if the comp valves are bad? Should have tried to pump down. At a loss with this one, any help would be appreciated.
    This is the reason for the bubbles.
    Stuart
    Lack of airflow destroys compressors.

  10. #23
    Join Date
    Apr 2004
    Location
    Des Plaines,IL
    Posts
    1,018
    Quote Originally Posted by shaka View Post
    You are over charged.
    First sight glass charging is wrong with those conditions
    AC unit are designed at 95f
    When it's around 70 condenser is too efficient and subcools gas faster than normal.
    So sight glass will not be clear.


    Go back to basic
    Check superheat chart and input your conditions
    I believe it's 16 SH
    ignore sight glass.

    If they are going to run Ac with these conditions
    Then you will need a low ambient control
    To prevent freeze ups
    I have found the opposite to be true. If you have more subcooling, then you have more liquid and therefore fewer bubbles. Think about it, if your subcooling is low, then you won't have enough liquid to form a solid column feeding your metering device.
    Stuart
    Lack of airflow destroys compressors.

  11. #24
    Join Date
    Jun 2004
    Posts
    873
    Quote Originally Posted by mcewans View Post
    I have found the opposite to be true. If you have more subcooling, then you have more liquid and therefore fewer bubbles. Think about it, if your subcooling is low, then you won't have enough liquid to form a solid column feeding your metering device.
    So your his boss..

    So exactly how much sub cooling should he be trying to reach?
    You really want him to clear the sight glass?

  12. #25
    Join Date
    Jun 2004
    Posts
    873
    This the reason why you should never install a sight glass on small residential unit
    Someone always trying to clear sight glass on any conditions.

  13. #26
    Join Date
    Apr 2012
    Location
    Louisiana
    Posts
    719
    Did the OP edit his post I don't see where he said it was 70 outside.

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