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R134 Retrofit Procedures

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  • R134 Retrofit Procedures

    Getting ready to do my first retrofit to 134 for an 1987 GM vehicle. Back in the day, it seems that retrofit kits were all the rage and plentiful. Now that I need one I can't find not one in town. I know there are several ways and opinions on the best method. I'd like to see what my options are.

    Can anybody point me in the right direction? A search didn't get me anywhere.
    Last edited by 69-er; 07-02-2017, 10:33 PM.

  • #2
    You can get the fittings one by one and decide how far you wish to go.

    Please specify what vehicle this is. GM sold a lot of models including just putting their name plate on 100% non GM vehicles.

    Those kits that were everywhere are gone that had all possible fittings, all used Ester oil that I knew of sold by Interdynamics.

    Let's begin with what vehicle this is and if the system is partially operational now and if any leaks known are excessive now. If not when did it work properly last if you know at all and or why do the retrofit vs keeping it R-12?

    Also, what tools do you have now like gauges, a scale or what, vacuum pump and so on? Do yourself a favor and any suspect lines that may be leaking put some PB (Power Blaster) on those now for a chance they wont bust or strip threads and that's just a chance,

    Tom
    MetroWest, Boston

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    • #3
      To add to the question why retrofit: This link from prior site has some insight on a specific vehicle but the issues remain the same. Sorry most sub links within this are not working or expired.

      > http://www.aircondition.com/tech/que...it-to-R134a%3F

      Another is charging procedures a long read and worth it.

      > http://www.aircondition.com/tech/que...ing-Procedures


      Tells of pressure differences to expect. I'll add you can expect without some serious alterations to condensers and fan power you'll lose about 20% of the OE potential performance in the BTU power of the system and add higher chances of leaks and future failures so lots to think about,
      Last edited by Tom Greenleaf; 07-03-2017, 07:46 AM. Reason: Add a link
      Tom
      MetroWest, Boston

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      • #4
        Thanks Tom. It's an 87 Chevy truck R20 with a 454. It still has a partial charge of R12. It's been sitting for several years so the leak is probably small.

        You made me second guess my decision about converting. Maybe I should see about the availability of R12.

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        • #5
          The big rush was in the later 90s into 2000s when R-12 had already quite making new and got wildly costly plus needed the cert to buy it. There was tons made in anticipation so no shortage still. It's recovered dare I say mostly from commercial walk in refrigeration and freezers worth it for the amount you could get all at once.

          It's made new in countries that didn't choose to comply to quit making it apparently not that difficult as a product goes. It's a large molecule the least corrosive, non leaking fast anyway with the most "caloric value" of anything ever made by mankind. Water being "One" and R-12 as close as anyone could make for that value.

          It's takes more of it, works fine with tough components where 134a really needs weaker high efficiency stuff that busts easily where I am from a stupid stone in the road there it all goes with one smack to a condenser.

          You can search out costs per pound to buy or ask locally who would just do the vacuum and charge if you have every reason to believe system is OK. Was said by car makers new now took that back or deleted the claim that you could expect to need a boost about ever 7 years so new added the extra - an overcharge on purpose to cover that usually as long as anyone would care short of an accident or other failure they just kept working.

          WHAT HAPPENED? Wasn't my job to rush to change to a less product now said (depends on what you believe is proven not much is) is more harmful and causes more problems for the longer run. Heck - you still have an 1987 with it at all shows something?

          Ask around. This link above shows costs for converting vs costs of keeping it simple. One problem is what is left in your system is going to be hard to find someone in biz still maintaining recovery equipment to save any of what you still have in there.

          Sitting several years can make this it's own problem with A/C and an assortment of things the truck didn't like will out cost just firing up a R-12 slow leaker of that vintage. Or was just the A/C left sitting unfixed for several years?

          You really can't know how much product is in it just if it's empty. You can know it's effectively empty by knowing the engine area temp for sure and just take a low pressure reading with a non running cold engine. If you are around 75-80F area temp the pressure should be no less than that just a pressure check in PSI like for a tire. If less it's considered empty.

          Where do they leak? Shaft seals of compressors most often for me mostly from exposure to super cold if vehicle is outside for Winters. Still have and use an OE 1989 just boost about ever 3 years a little. Left outside once and it was almost empty! Not again the vehicle is still excellent all around not used in Winter at all.

          This is just a decision for you to make not me I just brought it up as so few will still use R-12 in biz for A/C work even as demand is low so should prices.

          Best thing is this is a truck most parts are available forever for trucks even when old and ugly a useful vehicle/thing and new whole truck so costly you can fix a lot it not all rusted out I'd say worth it to keep. As of right now unknown what A/C really need to work unless you can test for any pressure as said and try it and see if compressor even just clicks on now for a second and quits would be good news,

          Tom
          MetroWest, Boston

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          • #6

            The latent heat (ability to absorb heat) for R12 is 68.2 BTU/lb, Where as 134a is 89.3. 134a has a greater capacity to absorb heat per lb BUT less lbs per cubic ft of liquid. So the two things counteract eachother. more heat per weight less weight per volume. There is a crossover point where 134a is actually better at cooling (lower temps) than R12. With 134a in auto air conditioning, less weight per volume, means the condenser (and to some extent the evaporator) ideally should be larger to transfer the same amount of heat.
            http://www.tecumseh.com/~/media/Nort...n-of-R134a.pdf

            I think it is explained in that link fairly well.
            It is why I recommend "oversizing" the condenser when a condenser need replacing when changing from R12 to R134a.
            Ideally one would like to "oversize" the evaporator a little also, but that is almost never possible, and since the evaporator temp is near the "cross over point" of R12 vs R134a it doesn't make as big an effect as increasing the condenser.
            It is also why you add "less" 134a by weight than R12 for a conversion. The same volume of R134a will weigh less than a identical volume of R12
            Last edited by Cornbinder89; 07-03-2017, 11:48 AM.

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            • #7
              The push for R 134a to replace R 12 was over ozone depletion and not "global warming". All evidence is that it worked and the ozone "hole" has got smaller or is gone entirely. Now the big new thing is climate change and even R134a doesn't help that, which is why we are seeing R1234y coming into play and may see CO2 as a refrigerant sometime in the future. With all the "problems" it is easy to mix up which one what is "responsible" for. Often it seams the "fix" to one causes another!

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              • #8
                Can discuss if any impact but isn't the point now that it's harder to get known good stuff. Did we ever I question? In short factor the costs and how long you think you'll get out of this truck as a whole and useful truck presumably not just a luxo truck just because you want it.

                My experience with if smaller cab trucks no dual air is that A/C was overkill when new and still could be in great shape. If you've already decided let's get going on exactly that,
                Tom
                MetroWest, Boston

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