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Diagnosis help

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  • Diagnosis help

    Working on waking up an aftermarket R134 system that's been dormant for a couple of years. Charged with 2lbs per the mfgs specs. Getting no cool air at the vent. At high rpm, ambient in the high 90s, Low side is 50psi, high is 125. Adding more charge made no difference. With my dated diagnosis skills I'm thinking bad compressor or expansion valve stuck open.


  • #2
    Both are a possibility, Tx valve change is the cheaper of the two, but if you are testing at 1500 rpm or greater, I would expect higher high and lower low even with a stuck Tx.
    Might be worth pulling the refrigerant back out and testing the compressor by putting you thumb over the outlet while turning the shaft by hand, should build pressure against you thumb, if not, then it is the compressor.
    The more I think about it, the more the compressor seams to be the problem, although if it sat for some time, a drier and Tx valve should be replaced as well.
    Last edited by Cornbinder89; 06-16-2019, 10:06 AM.


    • #3
      Pressures too low for 90F so no cooling with just that. Now, why if known was this dormant for years! Aftermarket of what type - exact fit to something or something all rigged you did have some suggestion of charge weight found.

      IDK if know this sat and was just open to weather I doubt much of it is going to work.

      Almost doesn't matter now but did this even hold a vacuum or perhaps skipped that step?
      MetroWest, Boston


      • #4
        Classic Auto air system for an early Mustang. It wasn't left open. It was recently discharged for other engine work. It hadnt been used for a few years, but still had a charge. It did hold a vacuum over an hour before I charged it.


        • #5
          ? IDK, ones I recall by then called ARA (?American Refridgeration A?????) something were on the floor or under dash junk didn't work when just put in as well as opening windows!

          I just vaguely recall a hokey mess of shims holding a noisy huge and heavy compressor unknown something and just hose and clamps no better than good heater hose going to the things.

          A whopping one had OE A/C if mean the 1960s the early Ford Falcon chassis/unit body even that a long time ago marked all over it FoMoCo stuff and "Dessert Air" by Ford. 4 row radiator. Was a restoration then at least 25 years ago all stickers, crayon marks from new in place REDONE to OE not a true untouched original but indefectible as new. I'm honestly not sure it wasn't just Ford authorized aftermarket air?

          Other than that one car never saw a Mustang or late Cougar of the 60s (if that's what you mean) with A/C at all. If one of those you'd wreck it by using aftermarket looking anything by now. Not my choice it's yours but if a real nice antique (now) or some call classic why wreck it?

          I don't mean the Mustang II or newer is still old now.

          What is this car if a classic real Mustang you can get almost anything hacked/cloned to look OE and work as OE for each model to a point.

          The very early systems I recall and worked on just some didn't even use Shrader valves rather "Stem" valves for compressors new or aftermarket such that you could remove compressors without discharging the whole system very totally meant for R-12 and "home" R-22 systems only the real stuff not some fake is abundant still if you trust what you are getting is another problem.

          I defer this to "Nacho" a moderator here but not here often has his own site and place new or older in Hermasillo, Senora, Mexico is reachable from here in member list early on from the original site this came from AND the one before that.

          In short your pressures aren't enough to work if classic and this aftermarket why are you bothering with it?

          Other: Aftermarket now is vintage a problem was pully of compressor was large so didn't gain RPM higher than engine RPMs just size and adding a pulley you'll gobble up water pumps. Other issue was the % of the pulley a belt rode on wasn't enough till serpentine belt use,
          Last edited by Tom Greenleaf; 06-17-2019, 12:30 AM. Reason: full of my typos!
          MetroWest, Boston


          • #6
            This isn't an adapted or hodge podge system from the 60s


            It's a system from the above company. Installed about 20 years ago.


            • #7
              OK: We are both thinking and searching stuff at the same time. Nacho can be reached here >> Nacho <<

              I defer it to him probably knows aftermarket better than anyone I know including all these vehicles what to do and what works best,
              MetroWest, Boston


              • #8
                One possibility is that when the system was open, some dirt got in the compressor holding one or more of the reed valves open.


                • #9
                  Quite possible