Climate Control Issue
1. The electrical part of the ignition switch is bad. Burnt contacts inside prevent power from going to the push-button unit when the ignition is "ON"
2. Bad push-button control unit. Very common problem on MBZ.
I had an '86 300 E a long time ago, and mine had both of those problems occuring. The ignition switch was $18 from the dealer. The push-button unit was around $200 re-built. A friend of mine had a 92 300E, and when my blower went off, I suspected the push-button, so we swapped it from his car into mine and it started working. That's how I determined it was the unit that went bad, before I spent $200.
I am just in the habit of turning the key to the right place when I start it now, so I don't even notice the problem anymore....
Maybe if you fiddle with your key, you can get a better idea of what is going wrong?



