circulating air-pocket in refrig. lines...
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  1. #1
    Join Date
    Jan 2005
    Posts
    152

    Unhappy

    30,000BTU air-handler & condenser (1988 Carrier) A/C only. I know that when the sys. comes on, there's alot of bubbling & hissing of the refrig. lines as the freon pressureizes. However, it should dissapear at a point. I've got air-bubbles in the lines after the comp has been running for an hour straight.

    The bubbles will go outside & can be seen thru the observation glass, then will come inside & can be heard right where the high-pressure line connects to the evap. coil. Then the whole thing repeats; the inside gets quiet, but the bubbles go back outside.

    Had the system evacuated in May 2004, but the SAME problem exists. The split is better & the air is colder, but I've still got bubbles. I saw the tech guy drain the freon back into the canninster & use a vaccume pump too.

    What gives?

  2. #2
    Join Date
    Dec 2004
    Location
    Robards KY
    Posts
    269
    You gotta have leak somewhere.

  3. #3
    Join Date
    Nov 2001
    Posts
    1,874
    Those are not air bubbles.
    Your seeing liquid refrigrant. Refrigerant changes from a liquid to a vapor in your system. The observation glass is called the sight glass. On a properly chaged and properly running unit this glass will appear empty. But it is actaully full of liquid refrigerant. When the charge has leaked out, you'll see the bubbles.
    If you try to fail, and succeed.
    Which have you done ?



  4. #4
    Join Date
    Nov 2002
    Location
    emerald city, sc
    Posts
    1,469
    paint over the sight glass. unless it is located at the inlet of the expansion valve it's not much use any way. it's time to find the leak. if the leak is in the coil it's probably time to consider a complete change out.
    i wanted to put a picture here

  5. #5
    When you say you saw the tech drain the freon back into the cannister what type of cannister are you refering to?It sounds like a full evacuation of the system may not have been achieved.

  6. #6
    Join Date
    Jan 2005
    Posts
    152
    >When you say you saw the tech drain the freon back into >the cannister what type of cannister are you refering to?>It sounds like a full evacuation of the system may not >have been achieved
    ___________________
    He drained it into another canister that looked like a freon container. He said, "you have to do it this way now, you can't vent it right off, because of the environment..", but I knew that.

  7. #7
    Join Date
    Jan 2005
    Posts
    152
    >>>>Your seeing liquid refrigrant. Refrigerant changes from a liquid to a vapor in your system. The observation glass is called the sight glass. On a properly chaged and properly running unit this glass will appear empty. But it is actaully full of liquid refrigerant. When the charge has leaked out, you'll see the bubbles.
    ______________________________
    The refrigerant is supposed to change state in the Evaporator and Condenser, not in the lines themselves. In other working systems, the site glass becomes clear (solid liquid refrigerant) but mine gets clear, then the bubbles come, then it gets clear, etc etc..

  8. #8
    Join Date
    Jan 2005
    Posts
    152
    >>>>it's time to find the leak. if the leak is in the coil it's probably time to consider a complete change out.
    ________________________
    However, the appearance of these bubbles *never* gets any better or any worse. Would the line-dryer be to-blame for this?

  9. #9
    Was the refrigerant reclaimed or was the system just pumped down and then evacuated? Big difference! The leak could be in the condensing unit itself which would not show up through a pump down.

  10. #10
    Join Date
    Nov 2001
    Posts
    1,874
    If the charge is not correct it will change state before or after the desired location in the coils.
    It could only be a matter of inches but that greatly effects the capacity of your system.

    IF YOU SEE BUBBLES IN THE GLASS, and you have had issues with a leak in the past. You still have one.
    Those are refrigerant bubbles not air.
    As I said, in a properly charged system, that glass will be full of CLEAR LIQUID refrigerant.
    When you lose charge it will show up as bubbles in the glass.

    Maybe you should put tape over it, so it doesn't bother you. And call your service man in the summer when you lose all the juice.
    If you try to fail, and succeed.
    Which have you done ?



  11. #11
    Join Date
    Oct 2004
    Posts
    3,400

    Gas & go!

    A sight glass is a crutch for those that can't measure subcooling. Completely unnecessary, and even will give bogus information if misapplied. It should NEVER have been installed, especially if your system is critically charged.

    Find a contractor that is willing to work without one.
    INSIST that it be removed from your system or proven that it needs one. If you can learn to ignore it, it will not cause any harm.

    Automotive air conditioners ALL used to have them.
    NONE of them have one now, unless some shade-tree installed one as aftermarket.



  12. #12
    Join Date
    Sep 2004
    Posts
    3,157
    We learned in school to let the smoke and air out at the same time

    But if you are using a blended "freon" it will take forever to get all of those air bubbles out of the system, unless you use an icepick

  13. #13
    Join Date
    Oct 2004
    Location
    Texas
    Posts
    1,172
    Your system could be low of refrigerant like others have stated, or you have a fixed restriction metering device such as a piston or capillary tube. With fixed restriction you will see bubbles at site glass and hear a combination of liquid and flash gas.
    Saddle Up!

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