Dunno for sure but you should be able to test the blower itself to see if it is ok. You should be able to disconnect the terminals going to it and jumper 12v to it. If it turns then you know it works and is not bound up, brushes ok, etc. If not it is easy enough to replace.
The blower I believe should be under the passenger side of the dash/footwell. It may not be the case.
As for the location of the fuse, maybe a fellow 300E member can give you some advice.
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