I'm pretty sure that it's not the Climate Control Unit, a faulty transistor inside can make the unit (and fan) not to shut down after ignition off. But that would only introduce a 0,5A current draw, not ten times more.
You'll find details on this fault and how to mend it
here.
You get the CCU out by pushing the wiper stalk to the fastest position and pull the unit out using normal Blaupunkt tools (or made from a coat hanger) The CCU is fused by Fuse 1, 17 and 28.
Maybe there's a short in the starter or in the generator circuits? Just a thought.
Cheers,
Tore