Well, the local dealership found the leak - it was a cracked condenser near the bottom (near outlet?). Obviously, the condenser will have to be replaced.

I've read through lots on A/C in this forum and it appears wisest to maintain the system as an R-12 system.

What options do I have with a new condenser for my 1989 300E? Is there a parallel flow model that I can use? Or will the 1989 style replacement be satisfactory?

Replacing the receiver/drier is virtually mandatory. No issue with that.

I've also read that on a car this old that it is wise to replace all the O-rings. Are they present at every thread fitting? I'm a little hesitant to open fittings on a 16 year old car lest I damage the pipe (ie the evaporator).

Would it be prudent to replace the hoses? This is an expensive option as one of the hoses has the fuel cooler attached.

Would it be prudent to replace the expansion valve? This part is not significantly expensive but access and age concern me for potential cracking or other damage.

By the way, the dealer recommended that I repair with STOP LEAK and convert to Duracool. Total repair and conversion cost was quoted as $1500 CDN. Sure glad that I was well informed by this forum. This won't happen!

Look forward to your replies so that I can collect parts and schedule repair time.

Thanks all,
Paul