I have switched all my cars from R12 to R134 without any problems, although the R134 does not get as cold, with recirc on it gets down to 48 degrees, plenty cold for Seattle summers. My 190 was done two years ago with no issues. One thing to remember is to charge your system to 80% capacity. Of course when I did this switch, I replaced my evap unit, ac filter, condenser and all the O rings. By the time I was finished there was little if no R12 oil left in the system, the only thing original is the compressor.