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Leaking Service Port

Last summer I started having a problem with the Central A/C in my house losing charge. I used some leak detector liquid and sprayed all the joints and had no luck locating a leak. A friend of mine that was in the business for years didn't have any luck either and no longer has an electronic detector. Defeated, I figured the best bet was to get an HVAC contractor out to locate the leak. I contacted a local company and they came out, sprayed all the same places I did, and couldn't find a leak. I asked the tech. if they had an electronic leak detector and was told that the owner finds them unreliable...... in the end they suggested putting a chemical into the system that would seal the leak which was NOT going to happen. In disgust, I bought myself a ZX-1 leak detector. In 20 minutes, I located 2 leaks and confirmed them with the bubble liquid..... very tiny bubbles you'd never see if you weren't looking at the exact location. One of the leaks is at the service port. I've bought new brass caps with o-ring but it still seems to leak. Does anyone have any tricks to cap the service ports?

On a happy note, the owner of the company did send me back my money for the service call after I told him I found the leak in 20 minutes with an electronic sniffer. He wanted to know what model :)


  • Techman
    Techman Member Posts: 2,144
    edited July 2010
    Lets make a deal!

    You tell us where the other leak is and I'll give you my advise.                                   O.K.,the service port is for the refrig gauges and has a replaceable Schrader insert that can be swaped out ,under pressure w/ a special tool, or the insert may be loosened [unscrewed ] a little  and then retightened also w/ another special tool,both ways might release a little freon,Di Minius applies here. Or you can get a Schrader T or a Schrader straight fitting and screw it onto the leaking Schrader service port.Or you can get a HARD BODY 1/4 " flare cap w/ flare gasket and double wrench it onto the service port. I like the Schrader adapter.Your turn!!!!!!!
  • Brent H.
    Brent H. Member Posts: 136
    The other leak....

    The other leak is up in the coil in the air handler. It's in one of the U shaped pieces of tubing on the side. I'm waiting for the cost of a replacement coil. The system is 10 years old so I'd rather just replace the coil than try to repair it.

    Out of curiosity, why doesn't the new brass cap with an O-ring that I installed on the service port prevent it from leaking?

  • Techman
    Techman Member Posts: 2,144
    ho ho ho

    Now you want more! Its hydraulics !The freon leaks past the insert, into the area of the cap,and builds up pressure,the pressure area in the cap then forces the pressure past that goofy o ring. That brass cap and o ring are more of a "dust"cap than anything else.
  • Mac_R
    Mac_R Member Posts: 117

    If the indoor coil is leaking your best bet is just replacing the entire coil.  That can not be fixed.  the capillaries that are in there are just to small to braze.  the leek at the service port can be fixed by replacing the valve core using a valve core replacing tool.  they are not on the cheep side but much better than a leek detector.  With that tool and a new valve core thirty seconds at most.  If the system is ten years old you might want to think about just replacing the system.  it is more expensive than just a coil.  however with all the tax incentives out there you might be surprised at the cost.  just saying. 
  • Unknown
    edited July 2010
    Curious A/C leak,

    Are you speaking of the Schrader ports where you attach the manifold guages?,,, or the service valves themselves that are opened with an allen key?

    I have had the latter leak too.
  • Brent H.
    Brent H. Member Posts: 136
    Schrader Port

    It's tough to tell but I believe it is the Schrader Port. There is pressure in the brass cap when I remove it. I have a new coil on order and will just replace the cores when we change the coil. The cost of a new coil is cheap as compared to a whole new system.... if it buys me 5 years I'll be happy. 
  • tim smith
    tim smith Member Posts: 2,544
    Re: leak at return bend

    If its leaking at a return bend on coil, we have repaired those many times. If you are just trying to get 5 yrs out of the deal, that would be my preference. If you were able to see the leak, usually you can fix the leak. Tim
This discussion has been closed.