I've unplugged the Blower Speed Controller and shorted POWER (#12) to BLOWER MOTOR (#6). Fan turns right on. Not the fan. Power is going to the BSC. Worked yesterday morning. I rebuilt my CCU, and it at least partially works (the aux pump seems to kick on), but not sure whether it's the BSC or the CCU at this point. There isn't much in terms of testing the BSC out there. I found one transcript of a diagnosis and am looking at that now.

http://www.justanswer.com/mercedes/0z76p-ok-guys-i-m-back-still-working-82-mercedes.html