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Thread: AC r134a adapter on r12 service port

  1. #1
    absotively posilutely bytes311's Avatar
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    AC r134a adapter on r12 service port

    Hello all,

    My AC has been converted to r134a, so I have r134a fittings on both high and low side service ports.

    Today I noticed I was low on refrigerant due to a slow leak coming from the low side service port. I removed the low side r134a adapter (cheap plastic from Auto-Zone) and saw/heard the leak actually coming from the r12 valve stem welded to the hose. I went to NAPA Auto Parts and picked up a good quality low side r134a adapter, only to find it's shorter than the one I got from Auto-Zone. When installing, the new adapter immediately presses down on the r12 valve. And when completely tightened, it doesn't let me depress the valve on the new adapter.

    Do I need to remove the r12 schrader core before I install the r134a adapter?



  2. #2
    Delorean Guru
    Join Date:  May 2011

    Location:  Northern NJ

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    You should not have to, besides, if you try to remove the core you will release all of the refrigerant. During the conversion process, before charging with the -134 was the time to remove the valve cores. Some of those conversion fittings are cheap pieces of junk. Often they won't fit because of their size and there is not enough room around the fittings. If you overtighten them you can rip the service port right off, it is only soft aluminum.
    David Teitelbaum

  3. #3
    DMC Midwest - 815.459.6439 DMCMW Dave's Avatar
    Join Date:  May 2011

    Location:  Crystal Lake IL

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    My VIN:    05429

    With the really good (brass/steel) conversion adapters, there is a schrader valve as part of the adapter. If you can see through the adapter, it's one of the POS aluminum ones. Throw it away.

    With the good ones you should remove the schraders in the R12 fittings. If you leave both schraders in line, sometimes the inner one will get damaged, and at best charging is a pain in the neck (slow). If you break the inner one, parts can actually fall into the hose and then the compressor. How lucky do you feel?

    Yes, this should have been done when the conversion was done and the system was empty. Now you are paying for someone else's boneheadedness (is that a word?). Why compound the error? Evacuate the system, remove the valve cores, and install the good adapters. Then you and your successors won't have to deal with this again next time it needs service. It will.
    Dave S
    DMC Midwest - retired but helping

  4. #4
    absotively posilutely bytes311's Avatar
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    Thanks guys.

  5. #5
    Member klaus5980's Avatar
    Join Date:  May 2011

    Location:  Germany

    Posts:    57

    My VIN:    #5980

    I had the same problem... after 3 months my AC was empty with R134-adapters. I found out that the adapter was a little bit leaky.

    I mounted new adapters with fluid metal glue and used stainless steel bolts (5/16-18X1/2 - shorten to fit - the thread inside is very short ) with a copper-o-ring and blue liquid seal (Hylomar) on both sides of the o-ring instead of the blue and red plastic caps. 100% sealed!


  6. #6
    Administrator Ron's Avatar
    Join Date:  Jun 2011

    Location:  North GA

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    Club(s):   (SEDOC) (DCUK)

    The red and blue caps are just to protect the valve/port.

    There is a tool that allows you to replace the valve w/o evacuating the system.

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