I do vividly recall having to go on a roadside assistance call where a new 210 owner had his aux fan running in the garage on a cold, rainy night, no reason the aux fan should be running. It ended up being that rear fuse and relay module. MB had a bulletin out on this guys exact problem, it was caused by poor fit or sealing of the fuse box lid. A little water can get in that relay module and really screw things up. I went to his home and yanked the 40 amp maxifuse just to keep the fan from running.

Gilly