A?C problem on 1993 Mercedes-Benz 400SEL

When the A/C is on the driver side back seat floor gets very wet, please help.

The evaporator drain is probably clogged. It should be accessible from under the vehicle and easily cleaned out. I suggest having a repair shop do this for you if you do not have a safe way to lift your vehicle to clean it out. Here is a link to help you find a repair shop close to you: