No Cooling at driver's side vents

I only get heat out of the cooling vents on the driver's side of the car. Any suggestions on where to start looking?

The best source that I know of to understand the system is Johan and Sean's website. Here's the link:
http://bmwe32.student.utwente.nl/
"IHKA Components" is the place to start and they may have an email address where you can contact them directly as well.