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Help Converting R-12 to R-134

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Skippy, Aug 14, 2000.

  1. Skippy

    Skippy Registered Member

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    Has anyone done this conversion before. And can you tell me what has to be done, how the new conversion works. Any info about this conversion would be helpful.

    Thanks
     
  2. LittlePig

    LittlePig 1/2 ton status

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    Re: Converting R-12 to R-134

    I havea mechanic friend who has done a lot of these conversions. For the most part, there are just a few things to replace, including the dryer and some other stuff. However, he worked at a dealership, which had a procedure to follow. What he found was that it is key to get the old system as purged as possible, even to the extent of drawing it down to vacuum a couple of times to get all the oil out. Also, even if it says you don't, you will need to replace the compressor. Almost all the conversions they did came in a few months later for a compressor replacement anyway, so he said it is better just to replace it off the bat. r-134 is supposed to run at a higher pressure on teh high side, since it does not cool as well as r-12, so the compressor might make the difference between cold air and room-temp.

    Email: xiaozhu@my-deja.com
    ICQ: 84108805
     
  3. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Re: Converting R-12 to R-134

    I was quoted $700 dollars CDN for the conversion. it involves redoing your hoses because the molecules in 134 are alot smaller than those in 12, and can weep through the rubber. You also should replace the dryer(not sure why, though). The entire system then has to be purged and cleaned before you can refill it with the 134a. The good news is you can still use your old compressor, as long as the shaft seals are in good shape.

    The converted system works exactly like the old one, but 134a costs around $8/lb, as opposed to $60/lb for R12. If you plan on keeping your truck for a long tim, I would suggest the conversion because it's only a matter of time before the supply of R12 is gone....

    The only real difference is that 134a will cool approximately 11% less efficently due to the difference in the molecular construction......At least, that's what I was told!
     
  4. GONZO

    GONZO Registered Member

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    i have done about 50-60 of these conversions(not on a blazer , but on other refrigeration systems). you do want to make sure the system is completley flushed of all traces of the r-12 and it's oil. take it to an extremely low vacuum if you can(we used to pull them down to less than 100 microns).i have seen plenty of compressors go within a few months of the freon swap. i'm not an engineer, so i can't tell you why. just backing up what littlepig had mentioned.
    good luck!


    <font color=blue>85 k5 Blazer 4x4
    99 Trans am 30th anniversary
    79 Trans am [​IMG]
     
  5. turbo

    turbo 1/2 ton status

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    You won\'t like it for long

    It will work Ok for a while then the leaksing thru the hoses and the overlaod failing the compressor will teach you what a poor idea it is.
    Go for the hydrocarbons.
    They are cheep effieicen lower pressure as cool as R12 and won't hurt your system.
    You can use duracool enviorsave or roll your own with isobutane and propane fuel for camp stoves.

    Don't let the fear mongers worry you.
    Look at all the use down under with no incidents.

    134 is more toxic and has a lower flash point then the hydocarbon mix.
     
  6. Nike

    Nike Registered Member

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    Re: You won\'t like it for long

    Turbo - Never heard of this, could you expand a bit? I am installing a system in a project truck, and would like to go as economical as possible, but would like to have something that works when I want it to. Thanks Nike

    Blue
     
  7. Skippy

    Skippy Registered Member

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    Re: You won\'t like it for long

    Turbo Can you tell me more about this enviorsafe or duracool like were to buy it.

    thanks
     
  8. Fast

    Fast Registered Member

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    I had a friend recharge my R12 system with 409A which he says is what he has been using since the ban on R12. I known him for about 20 years and he has been doing refrigeration work for as long as I have known him and has never steered me wrong.
    Fast

    Fast 84 K5

    http://www.Fast.coloradok5.com
     
  9. windrider

    windrider Registered Member

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    When a friend who is a mechanic converted mine, he replaced o-rings, the dryer, added an orfice and a high pressure switch. The high pressure switch turns the compressor off so it won't blow off the relief valve on the compressor, when the pressure gets high. I really can't believe the molecules seep past thru the hose! To test the hose therory, put some dye into the system and see where it leaked.
     
  10. Blue85

    Blue85 Troll Premium Member

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    Re: You won\'t like it for long

    You want to use 21% Isobutane and 79% propane, by weight. You can actually modify a propane torch body with the proper flare fittings and fill it directly into the AC system using gauges. I am currently researching this heavily since there is no such thing as new R-12. Everything that you buy now has come out of someone else's system and has been cleaned up and resold to you at a horrible price. I can not vouch for the method above, but it can be made to have the same thermal properties as R-12.

    '85 JIMMY
    '90 paint/grill/trim 5"susp 33/12.5/16.5
    Fresh 350 B&M '87 TH700
     
  11. tom

    tom 1/2 ton status

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    Re: You won\'t like it for long

    Here is a great bulletin board for automotive A/C info and lots of R-12 conversion info. Try aircondition.com
     
  12. BlazerGuy

    BlazerGuy 3/4 ton status

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  13. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    In response to windrider's comment of disbelief- Have you ever heard of the principle of osmosis? If a molecule of r12 is a basketball, then the size of r134a is a golf ball. Add high pressure to the equation, and the smaller molecule can weep thru the hoses.............Why do you think that natural gas and crude oil is distributed in steel or polyethelene pipe and not rubber hose?
     
  14. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Another point to consider regarding the propane/butane relacement for R12, which I DID look at before choosing the R12- remember where your refrigerant cooler is!!!!! I'm not sure I want to be in a front end collision with propane running through a weak little cooler mounted in the crush zone!!!!!
     
  15. windrider

    windrider Registered Member

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    We put uv dye when my system was charged.....I'll be waiting for the seepage with my black light! I understand osmosis and pressure, but they use rubber hoses on r132 ac I'll still bet the o rings will leak before the hose will.
     
  16. LittlePig

    LittlePig 1/2 ton status

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    Yes, they use rubber hose, but it is a different blend of rubber. Also, R12 hose is old, so has thousands of small cracks in it, so even if new r12 hose was ok (it's not) old hose would certainly leak, especially under pressure.

    Email: xiaozhu@my-deja.com
    ICQ: 84108805
     
  17. istallion88k5

    istallion88k5 1/2 ton status

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    Question, I bought my blazer it had the coolant drained and uv die put in to make sure there were no leaks, none showed up but the guy never had it filled/recharged? What are the chances of the ac comp being screwed since it has been empty for 8 months, I mean should I take it to a shop and expect to get reamed with all new parts?

    If it aint a Chevy don't raise it up!
     

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