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Newbie trying to get the correct hoses

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  • Newbie trying to get the correct hoses

    Hi folks,
    My name is Pete, I'm in Denver Colorado USA and I have a question for you guys:

    I'm trying to get all my AC service equipment together and I'm looking for some help with my charge hose. I have a manifiold set and a recovery pump / tank and quite a few ac hoses. My problem is none of my yellow charge hoses have the right connectors on them, or at least don't match my other hardware. My manifold set has a connector that has 16 TPI on it, and my pump has a connector that has 20TPI on it. I'm assuming it's 1/4" diameter on both, but my threads don't match. Here is my manifold fitting:

    and here is my pump fitting:

    I'm new to this, and I want to do it right and get certified and everything, but I need the right equipment first. Did I do something wrong? Did I buy the wrong stuff?

    Thanks for any help!

  • #2
    The fitting on the gauge set is Acme thread (used on automotive R134a gauge sets) and the fitting on the pump is std 1/4 flare. You should be able to get and adaptor to put on the gauge fitting that has female Acme and male 1/4 flare, Then you can use a std 1/4 flare hose.
    Most newer vacuum pumps have multiple fittings on them for Acme, 1/4" flare and 3/8" flare, how old is your pump?


    • #3
      So it looks like I'll need one of these:


      and a 1/4 to 1/4 hose? I already have the hose, and it's yellow even. That works for me. My pump is used, I bought it on Ebay. I don't know how old it is, but it doesn't look too old. It'll pull 28"; I understand that's the best you can hope for in the Denver area. It only has the 1 fitting on the suction side. It looks like it's a field replaceable fitting, like maybe when it was new, it came with some others. Or maybe there's a filter screen in there, I don't know. Just learning the ropes

      There's a ton of literature out there and even more "how to" videos on good ol youtube. I'm also certainly open to suggestion on which sources of information are credible and which aren't

      Thank you for your help!


      • #4
        Yeap, that will get you going.
        In commercial refrigeration, R134a tanks have 1/4" flare, it is only in automotive they went with the Acme fitting. I guess they thought Automotive people were too dumb to be trusted.
        My vacuum pump has three fittings on it, 1/4" flare, acme, and 3/8" flare (for working on larger commercial refrigeration systems)
        the hose end will need a core depressor in it to open the valve core in the fitting. If the acme fitting in the manifold has a core already in it, remove that core before screwing on the adaptor. You can't have two valve cores in a row, the 2nd one will not be opened.
        Last edited by Cornbinder89; 04-29-2020, 05:41 PM.


        • #5
          I'm one of those dummies I have been a mechanic for well... a long time. I have my own shop now, and I work on heavy equipment. I'm getting more and more customers with requests for a/c work. A/C wasn't a thing in heavy machines a decade ago. It is now, I suppose.

          I have been reading and watching videos, so now I'm an expert, right? Sure. I have another question. I'm practicing on my own truck before I break someone else's stuff. I'm following the mfg pressures, temperatures, all that. I have 1.6 lbs of refrigerant in my system, and my pressures are right in there, and my outlet temp is good. All seems well, so I disconnect. I am not happy with the amount of refrigerant that comes out of the hi side hose when I disconnect. I'm sure there's a safety concern there somewhere with the high pressure, but my concern is simply the amount of refrigerant that comes out. That can't be right. What am I doing wrong? When I'm all done, I close up all my valves, and start disconnecting hoses, and there's quite a bit of refrigerant left in the hi side. Maybe 150 - 200 psi worth, and that translates to alot of gas in the line and gauge in the manifold. When I disconnect the low side, there's a tiny amount that comes out, if any at all. On the hi side, it's quite alot.


          • #6
            What kind of hose ends do you have? The quick connect type for R134a should seal when removed from the port. Shutting the system down before disconnecting will lower the pressure in the high side hose but raise in the low side Remove the hoses with the valves on the manifold SHUT. That will trap any gas between the canister and the manifold, the quick connects should trap gas between the fitting and the manifold. I don't bleed much out when I dis connect, and I leave a small can on the yellow supply line to keep air and dirt out when not in use.


            • #7
              I leave the system off a few hours so the high pressure side will go down, then I disconnect the high side fitting.


              • #8
                Originally posted by Cusser
                I leave the system off a few hours so the high pressure side will go down, then I disconnect the high side fitting.
                No,while the AC is running ( engine too) turn OFF the Hi side knob (red) on the quick coupling by turning anti-clock way, than open the red tap on the gauges ( make sure the blue tap on the gauges is closed) now as the AC is running open the blue tap on the gauges only a little bit just till you see the pressure on the Red gauge (Hi side) dropping slowly and will get @ the same pressure as on the Low side gauge.You have now sucked the liquid ( by opening the blue tap a lit bit only it is now vapor = acts as an orifice tube )form the Hi side back into your AC system,you can disconnect the blue valve now from low side .Turn engine off and wait no more than 5 minutes than you can disconnect the red valve from the AC system,nice and easy.


                • #9
                  Just this point: TMK Cusser is in an unusually hot area about now so how is best would be unique there and to gauge type in use. Off the exact topic engine heat releases UP when you shut down so by rights it hotter higher up where ports should be but are not always need to know all factors so you don't mess up anything or worse get hurt just as silly as hooking up and disconnecting to refrigerants,
                  MetroWest, Boston


                  • #10
                    Originally posted by Tom Greenleaf
                    TMK Cusser is in an unusually hot area
                    Yes, Phoenix.


                    • #11
                      I thought so from ages ago. Met ACPROF here (New England) on a lecture job thing around me. Laughed when locals to the heat would say that both of us had heard "But it's a dry heat" thing and he said to me but "SO IS A FREAKING BLOW TORCH!!" He is/was living there and may still but a great sense of humor about it.

                      Just happened to pass thru OMG 1967 (a tad young then) seeing a bank's thermometer/sign busting past 120F no telling what road surface temps were but seemed like tires were melting. OMG!
                      MetroWest, Boston


                      • #12
                        Yes, why in 2004 a foreign company bought out my employer, I was required to sell all my stock options. So I put a down payment on a 2-acre place with 2000 SF home 100 miles away, about 5000 ft. elevation, significantly cooler. In 2016 after 40.5 years, I was caught in one of the many cost-savings downsizings at age 63.5, got 52 weeks severance pay. Had 2 pensions plus my 401k, so fine.

                        I worked there 22 years before I ever got a penny in bonus; luckily, things got better paywise. After foreign company bought us, R&D ceased to be a fun employer....


                        • #13
                          I never opened the red valve on the gauges! That actually makes sense. I don't know why I didn't think of that - let it bleed down to the low side before shutting down. Thank you Nickyanc Also big thanks to Cornbinder - your advise on adaptors was right on the money. Just what I needed. I bet if I let the hi side bleed down to the lo side, in conjunction with leaving a can on the yellow line while in storage, I wouldn't have to bleed my manifold every time too. Good tip there. Thanks guys!