I recently had problems with my 1996 C220. The fuse that controlled the vacuum supply pump kept blowing. However, we did not know that it was the fuse at first, just thought the vacuum supply pump was bad. Once we found the fuse and saw that it had blown, I replaced it. But it kept blowing. I did a lot of reading on this site, and found out that the problem I have been having with my air conditioner could be the source of the problem with the vacuum supply pump. My brother-in-law disconnected the vacuum supply pump for me, but the fuse still blew out. I had him reconnect it, and decided I would not use the air conditioner. The fuse still blew!
So I started reflecting on some things and realized that it would not blow until I got home. Here's the thing... I keep my garage door opener on the sun visor over my passenger seat. Whenever I come home, as I'm nearing my house, I pull the visor down to use the garage door opener. It finally clicked for me... that fuse controls the interior dome lights, which includes the lights on the visor mirror. I pulled the visor out of it's little holder and noticed a spark. Realized then that that is why the fuse keeps blowing
Now... what caused it to start happening now? I just had my headliner replaced and apparently some wires are touching or a wire is not grounded properly or something like that. So... I will be taking my car back to the headliner guy so he can take it apart again to get those wires in proper order.
Just wanted to let someone else know this just in case they start experiencing problems like this after a headliner replacement.

Yea, thanks for the post. Isn't always the smallest thing in the most unexpected place that goes wrong?!

My E 320 T did the same thing but with the driver's side sun visor. Every time it was lowered it blew the fuse. The problem was at the base of the sun visor. Of course, all other accessories that work along with the sun visor fuse stopped working. It seems it is a very common issue with sun visors and M.B.s

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A. Rosich
CL 500, 1998
S 500 L, 1998
E 320 T, 1995 [Sadly sold ]