Hi all, Have a 1991 348 TS and I'm trying to get the AC working. When car was in for major service 3 years ago the tech working on he car said the compressor would was shot, system wouldn't hold a charge. Also converting it to 134a. Have purchased a new receiver/dryer p/n 33363, and a set of Viton green o rings to replace old (black ) O-rings. I'm a bit confused on compressor p/n, I've been looking at Sandon/Sankyo SD709 for the replacement, is this the correct one? Trying to keep the cost down. Also wondering if I should replace the expansion valve, have a p/n 154276 for that. The search for that part has come up very costly, is there a cheaper alternate? Any help appreciated.