Hello I have a w115 1975 300d , My heater fan, and wipers will stay on when I shut off the car. It has been this way al long as I have owned this car but I don't think MB designed it this way and suppose it must be an electrical problem.

If it is an electrical problem, any suggestions on which relay goes to these things and where it is located and how to test it. If not a relay, would it be the ignition switch? Or any other ideas?

Much Thanks,