OK. Here we go. I have a 1990 Mercedes 190E with kind of low miles for its age. Nice car, runs well. The problem is that the blower for the AC, heater, and defroster won’t go on when it’s cold or wet outside. Sometimes while I’m driving it will suddenly turn on. Sometimes if I restart the car it will go on; sometimes stays on, sometimes goes off after a bit. When it’s dry and/or warm outside - no problem; on whenever I want, stays on, no problems. I have checked and replaced the fuses and I have had it at three different repair shops and thye all insisted that it was the center console control that was causing the problem and now I have that whole unit replaced and it has not fixed the problem no matter what I tell the mechanic. I get it that it’s an intermittant problem making it harder to identify but if anyone has an idea I’m willing to try it. Thanks!! Dave
Sounds like moisture problem in connections. Try dialectric grease in all the connectors.