If you are asking why the 400E gets checked. Its because there is a leak, AC will work for a few months. When I have brought it in they have said it holds vacuum but obviously there is a leak.

From what I know about W124's its likly to be berried in the dash. I am not going to have an AC place take the dash apart to fix it $$$. So unless I start working on AC systems myself its get it topped off yearly.

Just-n-time
Can you be a bit more specific (or state where to get specific info on converting an old compressor). Obviously the propane tank wold be used for recovery. However how do you rig everything up for proper recovery????

Paul