Mercedes M320 Air Conditioning Problem

I have a 1999 Mercedes Benz with about 145,000 and the air conditioning was not working well – took 15-30 minutes for it to kick in and start cooling the car. The mechanic, who specializes in Mercedes but is not with a dealership, replaced everything accessible for a considerable fee saying that there were several different places that were leaking. After a few days, it ceased to work at all. Now, the a/c never kicks in. The mechanic says it must be the evaporator, which for parts and labor is several thousand that I don’t have…Has anyone come across this…? Suggestions?

A Benz expert I’m not so off the top of my head I’m not familiar with how the evaporator and case is laid out.
However, I would have doubts about a mechanic who replaces a ton of parts without making sure all of the bases are covered (a.k.a. 12 gauge shotgun approach) and handing a car back to you without making triple sure the system is not leaking.

While I have no idea of the mechanic’s methodogy on any diagnosis I would advise getting another opinion. First off, the evaporator hose connections should be inspected to make sure this evaporator leak is not a simple and inexpensive O-ring leaking.
The system should get a partial charge at least and then an electronic sniffer used in the dashboard vents to verify if the evaporator is really leaking or not.

Many mechanics use dye to inspect for leaks and that can be a somewhat iffy method on an evaporator that is enclosed inside a case. The sniffer is much better.
Hope that helps some.