I have a mid 86 model that has the blower fuse mounted externally from the fuse box in a separate 30A fuse holder. This mod was performed by the factory on mid 86 and on 126's to prevent the melting of the fuse in the fusebox on your car. The upgrade is still available and very reasonably priced. I updated my blower fuse on my 85 380se this summer. Apparently as our blower motors age they draw more current than the original 25A fuse and fuse holder in the fuse box can handle.
I still think you have a CCU problem, but that is just my opinion sitting at desk and not even looking at your car. I am sure Pierre will get you fixed.

Good Luck

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John
1986 300sdl
1985 380se