Gee, sounds a lot like the problem I was doggin' for a few days (on & off).
After doing the obligatory fuse replacements (including the fan LINK fuse) then getting a diagram for the ACC (you will need a blind person to read it for you due the super bad scan on the CD), you should be able to trace the wiring at the control module.
In my case, (300SDL) the vacuum valves were working while pressing the buttons, but I could not hear them until I removed the module (good sound padding). Anyway, what I found was a bad diode in the fan control circuit on the module's pcb that would not give power to the fan (I design electronics).
After doing some trouble shooting with a DVM, you'll probably convince yourself that the module is bad. Wow, if only there was a place to get a good diagram! Could probably trace it on the pcb (if you are into electronics), as the circuit is pretty straight forward or shell out about $300 for one.
Its just too bad that most of the "help" that I got on the ACC was none and pretty much useless. My suggestion is you'll need to trace it out!