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  1. #1
    Join Date
    Dec 2001
    Posts
    57
    From an earlier post - I found the problem with suction line icing on my OD unit - a serious leak in the OD unit.

    Looking closer into the problem I was checking pressures and about to add freon and found everything very low. Then I noticed a large wet spot on the lower side of the OD unit. It turned-out that there is a leak on one of the high pressure lines inside the OD unit. I could actually hear the leak and find it at a T-joint inside the unit.

    The OD unit (along with the entire system) is only 3 years old (Carrier 38TUA 3.5 ton)so my hope is that Ic an get a replacement from the distributor.

    If I can't I'll go ahead and braze the leak but I have some concerns:

    1. Will I be able able to get a good braze with all the residue oil in the system? Seems unlikely.
    2. I normally triple evacuate the lines but can I do this with the compressor in the system - that is, on the compressor side of the service valves?
    3. Is there anything I could have done to cause this failure? The system ran perfectly for 2.5 years and the pressures and charge were fine tuned pretty well. Is there any known reason for this kind of failure or is it simply a rare manufacturing defect?

    Any comments?
    Scott

  2. #2

    purge with nitrogen

    Or your about to make phosgene gas. migneldoff's an free just does sound right...unless your a blue oval dealer..coil should be under warrenty...what would be easy the whole coil are brazing the tee. Oil + air = fire.
    Call a pro your in over your head.

  3. #3
    Join Date
    Dec 2001
    Posts
    57
    Well, according to Carrier only the compressor has a long warranty - everything else in the OD unit has only a one year warranty.

    As for being in over my head, I disagree and was hoping for more useful comments from this group.

  4. #4
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,358
    Originally posted by slimline
    Looking closer into the problem I was checking pressures and about to add freon and found everything very low. Then I noticed a large wet spot on the lower side of the OD unit. It turned-out that there is a leak on one of the high pressure lines inside the OD unit. I could actually hear the leak and find it at a T-joint inside the unit.

    If I can't I'll go ahead and braze the leak but I have some concerns:

    1. Will I be able able to get a good braze with all the residue oil in the system? Seems unlikely.
    2. I normally triple evacuate the lines but can I do this with the compressor in the system - that is, on the compressor side of the service valves?
    3. Is there anything I could have done to cause this failure? The system ran perfectly for 2.5 years and the pressures and charge were fine tuned pretty well. Is there any known reason for this kind of failure or is it simply a rare manufacturing defect?

    Any comments?
    Scott
    T-joint may have failed due to vibration. Not uncommon.

    1) Cut out the t and catch any oil that drains out. Purge the system with nitrogen.

    2) You can evacuate with compressor in system. It's done all the time. If compressor has king or service valves directly on the compressor, be sure they are backseated.

    3) Probably nothing you could've done to prevent this failure. Likely a weak joint that failed under vibration or pressure or both. Fix it, put a liquid line drier on, evacuate, charge and you're good to go.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  5. #5
    Join Date
    Dec 2001
    Posts
    57
    Shophound...thank you for the coaching and feedback. I was originally planning to just braze over the crack but, of course, ensuring that the joint was fully cleaned would have been difficult.

    I'll go ahead and replace the joint and fully open the system and from your instruction it sounds like I can go ahead and treat this just like I would any other joint (purge-recapture freon, clean, fit, fill with nitrogen, braze and then triple evacuate with vacuum pump).

    The unts do vibrate quite a bit, so I'll look to isolate them a bit better to absorb some of the vibration and noise (they're failry loud and rattly).

    Again, thanks for the help, it's much appreciated...

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