It isn't really recommended. Any decent shop can still repair your R-12 system and top it off with R-12. R-134 is not as efficient as R12, so to get the system to cool almost well they have to over fill the system with the R-134. The higher pressures are hard on seals. Modern vehicles use a larger compressor to make up for this. Also, unless you remove *ALL* of the old R-12 you'll have problems as the lubricants in the two refridgerants are incompatable. This will lead to problems with the system in a year or two. Doing it with one of the store bought kits is a good way to cost yourself money down the road. All in all, just stay with the R-12 and save yourself some headaches. Mark N VIN 6820 At 09:33 AM 3/20/00 -0800, David Jacobs (NEC) wrote: >Has anyone had any experience with changing the coolant for the air conditioner from R12 to R13? I have seen kits at the auto store that claim that it is a simple matter of just changing the coolant. However I seem to think that there might be more involved. > >Thanks! > >Dave >