I had the AC compressor on my '84 300D replaced in '98 and, as far as I know, all that was done was that the system was flushed and R134A added. Other than nedding to get a "fillup" every 2-3 years (Note: The car would sit idle in the garage in the winter), and the fact that R134A indeed is less efficient than R12 so things don't cool very well unless there's a full charge (Note: There probably isn't as much of an AC need in Rochester, NY as elsewhere). But when there's a full charge of R134A in my 300D, I've driven to NC in July without any problems, but of course I'm not one who likes the (GM) ice cold either.
G. M. Brown Rochester, NY
