This entire problem (lack of power to my climate control and window switches) began when I replaced two of the bulbs that light up the vent dials and one of the sockets sparked. After all the talk about the need to get the correct 3 watt bulbs for the instrument cluster, I am wondering if I bought bulbs that were too powerful.
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I had 1 bulb replaced about a year ago. In the process of removing the instrument cluster something happened...when I got the car back the whole right side wasn't working...RPM, clock, light, etc. This is what I was telling you about doing more damage than good. Anyway luckily the problem on my car was traced to a poor ground. Got a wire soldered to the back and grounded it to the frame...that did the trick. Everything works now. While everything was out, I had ALL the bulbs replaced with new OEM ones. I was going to go with higher watt bulbs, but decided against it after I read MANY post about melting instrument cluster.

Now to specically answer your question...you probably have a short. If you're lucky it's the fuse. Since you mentioned that you changed all your fuse, now you must search for the short. I would start from the climate control and window switches and work my way backwards.

One thing I've learn from owning this car is that you need to stick with OEM parts. Mercedes are very sensitive cars. Just buying aftermarket wheels can be difficult. The offset, bolt pattern, and width are very specific. Good thing about using Mercedes OEM parts is that once you fix it, it's good for another 100,000-200,000 miles.

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JR
1986 Gold 300E 4Dr automatic