Flushing the metal AC pipe

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  • Das Delfin
    R3VLimited
    • Sep 2014
    • 2293

    #1

    Flushing the metal AC pipe

    Hi all, I'm replacing my entire AC system because it's fun, using an LCA bracket housing a Sanden SD-7 and a Nissens parallel flow condensor and replacement evaporator and all available hoses as new, but I need to have two of the hoses rebuilt as they are NLA. (well one is only available as genuine brand for $120). The deal is you send in your old hoses, they retain the specifically bent metal pipes at each end, and put new hosing in the middle, but I'm worried about making sure the insides of these metal pipes are flushed out. This is a complete r134a conversion replacing everything with its r134a specific part and I don't want any cross contamination with different kinds of oils creating a bath of acid that destroys my nice clean brand new system I've spent too much money on.


    Also the long metal pipe that runs along the fender- my options there are spend money on a new pipe that is entirely clean AND comes with a native r134a port because it's cool, or worry about flushing out the residual oil deposits left in the line. My old AC system hadn't worked in years if not decades and the new system is a complete retrofit, with the exception of this metal pipe and the metal pipes that are part of the two hoses I need to have rebuilt, which are the return hose from the evaporator and one of the condensor hoses.

    What solvent should I use to flush them? Everyone online has their own opinions but I prefer the opinions here so give em to me!


    it's a Kenny Powers quote on wheels
  • roguetoaster
    R3V OG
    • Jan 2012
    • 7738

    #2
    There is specific AC flush out there, not sure of the composition, but something highly volatile. However, if the piping is rusty that's a whole other thing.

    Comment

    • monty23psk
      E30 Fanatic
      • Mar 2008
      • 1289

      #3
      I just replaced this pipe as the original service port was leaking. I got another original used one, got a newer version of an ac flush kit gun, and bought the solvent for it. Takes around 6oz for each pipe you want to flush and about 75psi using compressed air to the bottle. Bought both on Amazon for under $60. If the pipe is not rusty, I would remove, clean the outside with a mild pH degreaser like simple green, flush the line, and add new r134a compatible o-rings when re-attaching.
      Alex 88 m5 | 91 318is | 19 Subaru Ascent
      BMW Tool Rentals & Fender Roller

      Comment

      • 808ETA
        E30 Addict
        • Nov 2018
        • 429

        #4
        I flushed mine with the Autozone flush kit rental https://www.autozone.com/loan-a-tool...kit/326078_0_0 I used Temp Select A/C Flush Solvent https://www.napaonline.com/en/p/TEM4...pressionRank=1 It worked perfectly
        sigpic84 325e

        Comment

        • cory58
          E30 Enthusiast
          • Dec 2007
          • 1021

          #5
          Originally posted by Das Delfin
          The deal is you send in your old hoses, they retain the specifically bent metal pipes at each end, and put new hosing in the middle,
          Would it be possible to get the name/contact info for the shop that's making your new hoses?

          Thanks, Cory

          1992 325i Cabrio
          1988 320i Touring
          2000 M5
          1977 530i
          2015 328i - Euro Delivery/Performance Center Delivery
          BMWCCA
          E30CCA

          Comment

          • Das Delfin
            R3VLimited
            • Sep 2014
            • 2293

            #6
            I used brake cleaner until the line ran clean. I sent the old line to a place in florida called Cold Hose. They have a website. It was about $65 for the hose in the cabin that is NLA

            I'll likely be swapping an m54 into my car and I'll use them to make the fittings to fit the new AC compressor


            it's a Kenny Powers quote on wheels

            Comment

            • cory58
              E30 Enthusiast
              • Dec 2007
              • 1021

              #7
              Originally posted by Das Delfin
              I used brake cleaner until the line ran clean. I sent the old line to a place in florida called Cold Hose. They have a website. It was about $65 for the hose in the cabin that is NLA

              I'll likely be swapping an m54 into my car and I'll use them to make the fittings to fit the new AC compressor
              Thank you!
              1992 325i Cabrio
              1988 320i Touring
              2000 M5
              1977 530i
              2015 328i - Euro Delivery/Performance Center Delivery
              BMWCCA
              E30CCA

              Comment

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