years ago my AC quit,just left it this spring I had it looked at thinking new compressor but they both service valves were leaking.It never ran out of R12.Every summer I would run it to keep it from seizing and it worked,just recharged it and now works like new again.This year I decided to bring the car up to date.Changed Ujoints,Trans flush and fill,cooling flush and fill and new stock fuel pump.Now runs like new again.