My push button module has a defrost switch on it that runs the fan at high speed when I push the button. As for the temp control being unresponsive, I would suspect bad / dirty switches in the control. If you have one available, I'd try swapping it out for a spare.

Mine didnt work. I cleaned 25 years of crud out of those switches, replaced the electrolytic capacitors on the circuit board, and mine mysteriously came back to life. Electrolytic capacitors dry out over time, and go bad.

Best of luck getting your car to do as you want. I sure can't!

Bruce

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My first Mercedes Benz. 4/6/07.

1984 190E (201 024) 2.3L four.