Originally Posted by DANSMB

I know all the experts are not going to like this but I have been filling my AC systems for most of my 53 years and not following any of the rules. I have always had perfectly functionoing AC in all of my cars and just did another last month (1981 240D with 77 300D engine). I assemble the system then jump the low pressure switch to get the compressor running, now I take a small screwdriver and hold the high side shrader valve open with the engine running, it purges itself and draws a vacuumm, doing this at a high idle for 2 minutes has always worked for me. Now you need a 134 conversion fitting on the low side so you can add 3 cans of 134 ( one with oil). Done!!!!!! The new 134 cans with the built in gauge make it even easier to get the correct amount in. We have 8 cars now and have done this probably 30 times with no problems, no you don't need to change o rings, hoses, pumps or dryers. Good luck.

Dan