I feel rather stupid, but I've had my vanagon now for 4 months, and I'm still pretty perplexed to the ventilation controls and how to work them.  I have a 1987 Vanagon GL, with AC.  There's two knobs on the ceiling with a set of vents and the system goes down the center to the back, I assume that's the A/C since it has the little snowflake on one of the knobs.  

The controls on the dash are what confuse me....  there's four levers, two knobs (fan control), and that's about all I can decipher.  Anyone have "ventilation 101" FAQ or anything????

Thanks
Brady