A/C won't work when raining

[OrlandoMercedes]

I have a 1995 300D that I purchased over a year ago. Overall it has been a good car but when it rains my a/c doesn't work (windows fog over and very dangerous to drive). I have taken it to my MB mechanic and he said there is a clutch that won't engage to keep the compressor from burning out when it gets wet. He said all I can do is stop the car, remove the key, restart it and see if it will come back on. That hasn't worked. Has anyone else encountered this problem? Solutions/suggestions?

I have a hard time thinking there isn't some way to fix this. This issue is keeping me from using it as a daily driver. MB couldn't have designed a $40K car to not have a/c in the rain. Your comments are appreciated.