Going to recharge my AC...

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  • johne
    S2Forum Extremist
    • Apr 2007
    • 1406
    • Country: United Kingdom

    #16
    Originally posted by S2central.net
    John - you are the AC king !

    So I have this old V6 with R12 - its not working, but the only fault the HVAC controller throws up is to do with lower battery voltage than it would like - no errors about low gas pressure.
    Anyway - I would like to convert it to R134 (or RS24). Some questions then -

    1. Do I need to change all the seals ?

    >> No

    2. Do I need to change the restrictor (I think not) ?

    >> No

    And can you confirm that I need to do the following during the conversion process ---

    1. Replace the drier/reciever/reservoir

    >> Strictly, no...........but if the current system has ever been empty or had a leak the receiver/drier will have no ability left to remove moisture and that's bad. Also the old one will be contaminated with mineral oil which is the R12 lubricant. Given you should be able to get one from GSF for less than £40, I'd replace it if I were you.

    2. Drain / evacuate all traces of old gas and oil

    >> Yes, but as @S2driveruk says, at this point it's worth paying someone to evacuate the system and recharge with R134a and as part of that they'll check you can hold a vacuum for a while which is a good leak test.

    3. Charge system with PAG oil as compatible with R134 gas

    >> With R134a you can use PAG or POE oil. Manufacturers use PAG but POE has it's advantages. Most likely whoever you use to recharge the system will have an automated unit that adds the correct amount of oil along with the correct weight of gas.

    Finally though - the 1st thing I need to do is have the thing leak tested before I do anything - I have one of those leak test kits from interdynamics with the dye, lamp & goggles - are they OK for use on R12 and R134 systems ?

    >> Yes they are, but you also need to have enough gas in the system for it to run for the dye to get round all the system to look for leaks so there's a bit of a "Catch 22" here.

    Oh last question (D'oh) - Anything special I should look out for when hooking up my AC pressure guages onto this system - other than maybe funky LP port on the compressor ?

    >> The big thing we haven't covered so far is that the connectors on a R12 system are different to those on a R134a one so the first thing you have to do is get a pair of R12 to R134a adaptors. They will screw onto your R12 high and low side connectors and make them the correct size for attaching R134a kit - and incidently your gauges!

    I have seen them for sale in the UK - http://www.car-air-conditioning-supp...9&cat=0&page=1

    This is expensive when all you need is the adaptors which you can buy in the US on their own for around $10. I or someone could get you a set from the US.

    Cheers,

    Paul
    John
    Last edited by johne; 24 June 2009, 23:17.

    Comment

    • johne
      S2Forum Extremist
      • Apr 2007
      • 1406
      • Country: United Kingdom

      #17
      Originally posted by panzerwagen
      John, question....I have a 1990 CQ. And the guys who did the conversion put a 134 low side nipple there. Reading one of your earlier postings you said that the real "Low-Side' IS IN THE PASSENGER FOOTWELL...what car would that be?
      On my S2 but I have to be careful here. My S2 didn't come with A/C so I gathered A/C parts from various 80s/coupes and I never saw some of the donors. The R134a system I have has the low port by the low pressure switch on the evaporator in the passenger footwell. Bentley says the low port is on the compressor for your car.

      John

      Comment

      • S2central.net
        Retired OG Mod
        • Jul 2003
        • 16590
        • Country: Northern Ireland

        #18
        I am 99% sure Johne is right on this one - but I will double check with a look at factory info.

        PS - Thanks for the replies there too John... I wasn't going to dare do anything radical on this old system. By some curious fluke - I have an interdynamics kit for converting R12 to R134 complete with the adapters you speak of - I bought it while stateside to fix up the AC on a Ford Exploder (none of the local shops would touch it with R12) - but it turned out the compressor clutch was playing up and there was plenty of R12 in the system to keep things cool - very important in Hotlanta in July.

        Looks like step one is a leak test / vacuum out the old R12 - then renew the filter/drier if all is airtight - pop on the R134 valves and charge her up... Would be awesome to have a cool car again - in more ways than one - LOL.
        Paul Nugent
        Webmaster http://S2central.net
        Administrator http://S2forum.com

        1994 S2 Coupe ABY - aka Project Lazarus
        2001 A6 allroad 2.5TDi - family tank
        2003 S4 Avant 4.2 V8 - daily burble

        Purveyor of HomeFries and Exclusive agent for Samco hose kits (S2/RS2)

        There are only 10 kinds of people that understand binary - those that do, and those that don't

        Comment

        • UUUdirs2newcastle
          S2Forum Maniac
          • Apr 2008
          • 655
          • Country: England

          #19
          Originally posted by johne
          "ME
          Quote:
          Originally Posted by UUUdirs2newcastle
          The lads at Mercedes Benz workshop were going to re charge mine, but they could not get the lower nipple off the compressor. can I buy a new nipple? It seems that it is just unscrewing off the unit, rather than the aluminium screw cap coming off! " ----ME

          JOHN "

          If your compressor is like mine then the connector on the compressor isn't a standard low side A/C quick connect but a screw thread one that is difficult to use. The "official" low side A/C connector is on the evaporator tucked up behind the ECU in the passenger footwell.

          I suggest you get the boys at the Merc workshop to recharge your system through the high side port on the condensor (in front of the water radiator). Most of the automated recharge systems garages have these days can cope with just using the high side port - just don't run the compressor during the process!

          John
          So if we look can I find the quick fitting low side port under the carpet in the footwell?

          What pressure should they put in?

          Is there anything else they need to know?

          Cheers

          Comment

          • S2central.net
            Retired OG Mod
            • Jul 2003
            • 16590
            • Country: Northern Ireland

            #20
            I will TRY to dig up some data on this and post it today. I have long wanted to do a proper section on S2central.net on this subject... Guess I should just get wired into it - happens every Summer
            Paul Nugent
            Webmaster http://S2central.net
            Administrator http://S2forum.com

            1994 S2 Coupe ABY - aka Project Lazarus
            2001 A6 allroad 2.5TDi - family tank
            2003 S4 Avant 4.2 V8 - daily burble

            Purveyor of HomeFries and Exclusive agent for Samco hose kits (S2/RS2)

            There are only 10 kinds of people that understand binary - those that do, and those that don't

            Comment

            • PaulJ
              S2Forum Addict
              • Jun 2008
              • 253
              • Country: Scotland

              #21
              Hi guys, does anyone know the correct type of pag oil to use in an rs2, my old compressor was a zexel and have 100 pg oil marked on the label, my new compressor only has a hella / behr label
              1995 RS2 Nogaro
              1971 Lotus Elan Sprint
              1974 Lotus Elan+2S 130/5

              Comment

              • johne
                S2Forum Extremist
                • Apr 2007
                • 1406
                • Country: United Kingdom

                #22
                Originally posted by PaulJ
                Hi guys, does anyone know the correct type of pag oil to use in an rs2, my old compressor was a zexel and have 100 pg oil marked on the label, my new compressor only has a hella / behr label
                If it's filled with R134a and OE it'll be PAG oil. As far as I'm aware, although there are different brands, there's only one type/grade of PAG oil for R134a air-con systems.

                If it's an older R12 system that's been converted to R134a then it could have PAG or POE oil in it.

                The original R12 systems had a mineral based oil in them but given you can't get R12 these days you won't be needing the mineral oil - although I do have some.

                John

                Comment

                • PaulJ
                  S2Forum Addict
                  • Jun 2008
                  • 253
                  • Country: Scotland

                  #23
                  Hi John

                  Done some more digging today, Pag oils as far as i could see have 3 viscosities
                  PAG 1 is SAE46, PAG II is 100 and PAG III is 150, I believe the correct oil I need is ZXL 100 which is PAG I SAE46. As I cannot get zexel oil, I'll get an alternative

                  When fitting a new compressor how much oil should you add to the system ?

                  Paul
                  1995 RS2 Nogaro
                  1971 Lotus Elan Sprint
                  1974 Lotus Elan+2S 130/5

                  Comment

                  • johne
                    S2Forum Extremist
                    • Apr 2007
                    • 1406
                    • Country: United Kingdom

                    #24
                    Originally posted by PaulJ
                    Hi John

                    Done some more digging today, Pag oils as far as i could see have 3 viscosities
                    PAG 1 is SAE46, PAG II is 100 and PAG III is 150, I believe the correct oil I need is ZXL 100 which is PAG I SAE46. As I cannot get zexel oil, I'll get an alternative

                    When fitting a new compressor how much oil should you add to the system ?

                    Paul
                    Castrol PAG 1 SAE46 is what I have used.

                    A new compressor should come with 250ml of oil already in it which is the total system fill. If your new compressor has been supplied without oil I'd add 200ml (to allow for the other 50ml already being elsewhere in the system, rotate a few times then install.

                    Depending on how you plan to recharge the system most recharge machines will vacuum out whatever oil and gas is in your system then refill autmatically with the correct amount of gas and oil. Even if you plan to recharge this way I'd still oil and rotate your new compressor by hand before installing.

                    Note that PAG oil is like brake fluid in that it loves and absorbs water so it should be fresh and kept capped as much as possible.

                    John

                    Comment

                    • PaulJ
                      S2Forum Addict
                      • Jun 2008
                      • 253
                      • Country: Scotland

                      #25
                      Thanks John
                      1995 RS2 Nogaro
                      1971 Lotus Elan Sprint
                      1974 Lotus Elan+2S 130/5

                      Comment

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