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  1. #1
    Join Date
    Sep 2002
    Posts
    4,970

    converting r12 to 134a in older truck

    Got a 1993 chevy 2500 4x4 its just one of the backups with utility boxes . Used it the other day hauling some stuff and realized that ac is not cooling. being its r12 I thought I might look into just converting to 134a ....... ya like how longs 134a gonna be around ? Ok so is there anything out there that is not a huge hassel that works. I see kits all over that claim its simple ..... then you hear people changing about everything. Not gonna put in a lot in it but if its not all that bad it might be worth fixing it so when ever I want to get rid of it they have an air conditioner. Its still a real nice truck so I might as well have the ac working and I would prefer converting it so I have an idea what it takes so if I run into that situation again it won't be a problem. Havn't really looked to see where it leaked but thinking about it last time that that truck was raised up fixing a leak from some hose clamps I noticed some oil on some of the insulated lines under the truck , so I just pressure washed them thinking it might have been some antifreeze from the leaking hose clamps. Now I'm thinking ...... hmmm maybe its refrigerant oil. Guess I better look into it when it slows down

    so tell me your horror stories

    or how it was just a simple kit

  2. #2
    Join Date
    Apr 2003
    Location
    Maple Grove, MN
    Posts
    1,423
    I don't work on car air conditioners, but I would think that if you could get a different R12 substitute that is compatible with the mineral oil that is in your car (hotshot, r409a, etc), that it would be easier and would probably work better.

  3. #3
    Join Date
    Jul 2011
    Location
    Nanaimo,BC, Canada!
    Posts
    346
    Converting a r-12 automotive AC system to r-134A can be a pita.. On most you need to change all the o-rings, then there's the question of if the shaft seal in the compressor is compatible with r-134A and POE OIL.. And is the condenser large enough to handle it.. Oh and let's not forget the hoses!! Those need to be nylon barrier hoses.... Probably best finding a " drop in" replacement for r-12.. Keep in mind not all drop ins are approved for automotive use.. At least not around here anyhow..

  4. #4
    Join Date
    Dec 2003
    Location
    Citrus County, Florida
    Posts
    1,625
    that uses thr R4 compressor which does not hold a lot of oil. Why not just fix the leaks and use r12? You'll be a lot happier than trying to convert it. You'll need to use a better condenser for performance. R12 is still available especially on flea bay. I also have a good amount of r12 in 30 pound cyclinders and I also have some 14 ox cans if I can be of any help to you.
    Doug

  5. #5
    Join Date
    Oct 2009
    Posts
    984
    A thread a couple years ago helped me out. Went to 134a still works fine.
    Never argue with a crazy man.

  6. #6
    Join Date
    Jun 2008
    Location
    In the Boondocks near Marion, IN
    Posts
    119
    For a 1993 vehicle, 134A will outlast the rest of the machine. Have done a bunch of them with zero problems.
    Rick

    "It is easier to do things right the 1st time rather than to explain why it wasn't when you have to do it the 2nd time."

  7. #7
    Join Date
    Sep 2010
    Location
    Western, MO
    Posts
    871
    I've done a bunch of tractors and heavy equipment. Once the hoses and seals have been soaked in mineral oil for 10-20 years they don't seem to have a problem with R-134A.

    jim
    Common sense isn't very common anymore.

  8. #8
    Join Date
    Jun 2003
    Location
    Chicago, IL
    Posts
    4,564
    Just get the kit that comes with valve adapters, POE oil, and cans of 134a.

    I've done it over 10 times with no issues at all. Every one cooled at least as good as the r-12

  9. #9
    Join Date
    Sep 2002
    Posts
    4,970

    Thumbs up

    Quote Originally Posted by craig1 View Post
    Just get the kit that comes with valve adapters, POE oil, and cans of 134a.

    I've done it over 10 times with no issues at all. Every one cooled at least as good as the r-12
    that's what I was looking to hear. Just thought if the 134a would work that it would make more sense putting that in a truck that sets around a lot. You never know, I might stumble into some cans of r12 at rummage sales so that way your not paying out over blown prices like its out there for now. My fault for not keeping a 30 lbs bottle of r12 around but I didn't realize I had any more trucks using r12 around. It must have changed between 93 and 95 being 1995 2500 had 134a and 1993 2500 had r12. I just took for granted both had 134a.

    Thanks for the responses

  10. #10
    Join Date
    Jul 2011
    Location
    Nanaimo,BC, Canada!
    Posts
    346
    Automotive manufacturers began making the switch to r134a in 93.
    Legally can you still put r12 in an automotive systems? Here it's prohibited ..

  11. #11
    Join Date
    Jun 2003
    Location
    Chicago, IL
    Posts
    4,564
    I read somewhere on the Internet that the "new thing" is using r-152a, also known as computer duster. Apparently it has very favorable properties like low pressures and minimal environmental impact, and I believe they said it even works with mineral oil.

  12. #12
    Join Date
    Jun 2013
    Location
    Austin, TX
    Posts
    641
    R152a is a HFC so I wouldn't depend on it working with mineral oil. What might be an easier way to get around that problem is to add some R290 or R600a (very little, as in a few percent of the charge) as an oil carrier. It's even possible to use a mix of R290 and R600a as a replacement for R12. Some cite the flammability concerns, but if you think about it, the amount is tiny compared to all the gasoline in the back...

    What would be an interesting question is that if you use R152a from a duster can as a refrigerant, would you have to recover it afterwards?

  13. #13
    Join Date
    Apr 2008
    Location
    Bemidji MN
    Posts
    64
    I use R416A all the time in "mobile refrigeration". I believe it also goes by the name FR12. It works great and I think that you can get it in the small cans like R134a comes in. The R12 compressor and condenser that is currently installed in your truck will not have the capacity to cool the same using R134a. It will cool......but not like it did with R12 or one of the substitutes. If you were to compare the compressor from a 93' to a 94' (in 1994 they switched to R134a) the R134a compressor has a much larger displacement. Hope this helps!

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