Wipers and Heater Relationship (w201)

[DieselPaul]

So my dad is driving my 1987 190E 5speed as a winter car, and he has developed an interesting issue. Sometimes, when you turn on the turn signals the signals work, but it turns the climate control totally off.

Sometimes the turn signals just plain don't work.

Sometimes you hear a clicking in the dash like a relay clicking

Most of the time it works as it should, it seems difficult to get it to misbehave when you want it to to diagnose, but when it is acting up it seems to never stop until you get to where you are going.

Any ideas? I don't see how the CCU and the turn signal stalk are at all wired together.