I have an w140 400EL-93.I have the same PROBLEM. I CHANGED the V belt and Cabine (Evaporator) sensor, but no solution. Looking for the wiring diagram, the only relay is the auxiliary coolant pump control relay, but there is a base module computer. Apparently this base module releaf the relay. This is confusing me, since looks like a different a/c system, even for MB cars. No technicians want to work with this. I have to doit by my self. If I get A SOLUTION FOR SURE i WILL LET YOU KNOW. IF YOU GET IT fIRST ,I AM HERE.

THANKS

WILFREDO