The Air Conditioning is inop on my new 1970 300. It's lost it's charge. Due to the "preciousness" of R-12, I want to service the system "once and done", to whatever reasonable extent that is possible. Was thinking of new compressor bearings, shaft seal, oil change, and drier. At that point, pressurize with Nitrogen, leave it for like a week, check for leaks, Vacuum system, leave it for like a week, make sure there are no leaks before charging. Not sure about disturbing and breaking connections that maybe aren't leaking to change o-rings. Thoughts?