It never occured to me that the evaporator could be freezing since the air never really got that cold. I'm about to take the car out so I'll check if it is running when it goes hot.

I did do some reading in the MB climate control manual and discovered that my auxillary fan should be running any time the A/C is on. There is a high pressure switch (S32) that senses 20bar at the dryer and is suppossed to turn the aux fan on. Well, my aux fan has only ever turned on when the engine gets hot. I still don't know much about this system, but I suspect that the opposite may be happening, the R134 is getting too hot and something is shutting the system down to protect it. Just a hunch.

Anyway, I jumpered the wires at S32 and now the fan runs anytime the ignition is in run. I ordered a replacement switch - but the parts supplier called it a temp switch??? I'm sure it's the right switch since there are only 2 at the dryer and the other one is completely different.

Thanks again,

Bob