So the A/C on my ’91 745 Turbo wagon has failed. I believe it’s the compressor, as it was growling all last summer. This would be the time to switch to R-134a. I have a ‘rebuilt’ compressor and a ’92 receiver/dryer that I think I can use on the car. Where can I get the needed ‘O’ rings as a separate package?. Is there a handy-dandy parts list somewhere, or do I need to pull the parts apart and then go to an parts store and hunt and search?. How many do I need to replace the compressor and the receiver dryer? Any other tips, other than the comments on the FAQ? One last question: how do I load oil into the new compressor? The system is now empty of R-12 (sorry ozone layer), but do I need to worry about any old R-12 oil still floating around in the other components?

Thanks for any comments/help.