As a (hopefully helpful) note to anyone who digs up this thread in the future and has a similar problem...

Had the same issue but with the left window in my 90 300SL. Looked at the fuses in the trunk and they looked fine. Wasn't sure which one was for the left window motor anyway (there appears to be NO diagram anywhere of which fuse in the trunk does what).

Pulled off the door panel and tested the motor for 12V.. nothing.
Ran 12V to the motor and it sent the window up and down just fine.
Never suspected the switch, because (like the original poster) I could hear a click from behind the drivers seat when hitting the switch.. how could the switch be bad?

Then I found this post and looked VERY closely at the fuses in the trunk.

The very top one was all crumbly and it came apart into bits when I removed it. Put in a new one and everything worked PERFECTLY!

Then I spent 45 mins putting the stupid door back together which I didn't need to remove in the first place

So we now know two things...
1. ALWAYS check the fuses in the trunk first. Replace them all if you think anything is weird. Funny thing is, I've always replaced every fuse when buying a used MB. Never did it on this car for some reason....
2. The topmost fuse is for the left door window. Not sure what the others are but I would assume #1 is left window and #2 is right window.

Hopefully this is helpful if anyone has the same issue....

Neal

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