Proper R134a Conversion

Suggest you stay with R-12; the R134 isn't cheap anymore. So "topping off" with R-12 will probably cost a lot less than any conversion.

Prices on R-12 are way down from a couple of years ago. Fix your leak and re-charge with R-12. It will be cheaper and your AC will work much better.

Well thanks,... I think. I had heard that R134a was not cooling as well, but thought it was because it requires higher pressures . As I recall its been over 3 years since my system was recharged at 120.oo a pound, I think. Dye was put in, but I never went back since everything worked. I think this sounds like leaky O rings ......do you agree? Should I have the system "flushed and pressure tested" before refilling..... or just topped off. By the way flushed with what?

Whenever you change from R12 to R134a the only thing that really needs to be changed is the drier canister. Everything else will be fine, including the compressor. When you draw down the system you'll remove nearly everything from the R12 system including most of the oil so you will want to put in at least one can with an oil charge. If you do decide to switch over to R134a put in a can with a sealer included in the mixture. I've use this and it seems to seal any small leak I've encountered. Incidentally, I've change two of my own MBs to R134a with good results......cold and all that in warm, sunny S. Cal. However, having said all of this I'd do as the other fellows suggested and stay with the R12 as long as possible. It works and, in my humble opinion, has been thrashed by tree-huggers hoping to make a buck or two on companies producing R134a since they obviously lost out on the R12 bubble.

There are other refrigerants that will cool as effectively as R12 and are environmentally compliant. I would not fool with R12 in this day and age-the price only has come down because the demand peak is over. If you are keeping the vehicle I would do it right.

You can DIY if you are determined, you will need a vacuum pump and a manifold gauge set as a bare minimum. I would flush the system thoroughly and depending on which compressor your car has possibly replace it or open and flush it. Some compressors are user openable-I've done all sort of things with recip Tech and York units-although today if you had one of those old battle-axes I'd look into a Sanden conversion.