I think I'm beating a dead horse but I have a comment and a question. Yesterday I had my '89 300E in the shop to get the AC working. I knew going in that I would bite the bullet and pay for the R12 but when I picked the car up, I talked with the owner and he spent a lot of time telling me that he has done conversions in the past on many cars but has stopped and will not do any more. He does not do them for all the reasons mentioned in the previous posts. If I didn't know better, I'd swear I was talking to Stevebfl..............
My question.....2 summers ago, I had a leak that was repaired. The AC worked fine all summer and last summer but was blowing cold air this year. The shop that charged it yesterday pressure tested it and put dye in the system and everything looks great. If I'm losing all R12 in 2 years I must have a leak????? Any ideas where I could have a leak that is so miniscule that it doesn't show up in a pressure test and wouldn't be visible ????