Got another mystery with my 1984 190e. I noticed today as soon as I flip the headlight switch to any setting besides the 12-o-clock off position, my heater blower quits working! Soon as I turn them off the blower is right back on. I replaced the fuses for the blower and it did not make a difference. The car did have a hack job done to install a radio, but I took the dash apart and all heater control wires look fine. Anyone run into this issue before? Figured I would ask before I tear apart the dash any further to try to figure out what the hell is going on.

UPDATE

On the way home I was playing around with controls and noticed that if I turn the headlight switch to the right (parking lamps) it does not affect the blower. If I turn it to the right it shuts off, sometimes it comes back on when I turn the lights off, but not always. If it doesnt come on when I switch the lights off, turning on the left blinker gets it going again, but surprisingly not the right one. Any ideas? I think I am going to check the blinker switch tomorrow.

or run another 12V to the heater power, fused too.
Looks like someone had tapped into these wires, it can be very PITA to retraced again.

Or someone had moved the fan motor ground onto the lights +ve too. A lot of these wirings were grounded when no power is being feed thru as designed by the switch. Dont ask me why?
So who ever found this wire thought is a good ground, until u turn on the lights then it became a 12V. If u ground the + ve of the motor it may even work too. LOL.

When I got my 87 190e the starter switch ( as on the ign switch ) doesnt work, I had to tap a wire to the solenoid trigger wire too.
Slowly I traced to a wire that was the orig feed to solenoid, it did spliced into the car alarm/immobiliser. That wire comes thru the right side firewall to a box resides under the right/ passenger foot well.
As the Alarm doesnt work therefore the switch wont work. I join the wire back again, now I can use the ignition switch to start the car.
For a while I thought the neutral safety switch acted up too!

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SD,

thanks for the input. I am going to go check some connections and we will see what I can find.

Found the problem!

Before I went through all the wiring I decided to see if there were any 190s in the local U-pull-it yard, sure enough there was an 87 190 2.6 Auto. I noticed the controls are a little different but I bought the climate control unit, fan switch, and headlamp switch. After swapping in the fan switch the issue was still there, climate control unit solved the problem. I'll have to pull the old one apart to see what was going on

I did changed the light switch too. Mines failed and one can keep turning it.
The wrecking guy sold me a european 300se as it has a vacuum switch next to it, to do the headlight tilt.
There're obviously more connectors than mines. I slowly wrote down all the connectors and switch her over. My 190e does not need all the terminal, in the end they all worked.

Well thank God your system is all working now.

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