AC/heat controls

I have just recently bought 92 V6 Corsica. The car came with no manual. I have hard time figuring out AC control knob :screwy: . I know Normal, Max and Vent but would be nice to know what happens on the rest (whether AC kicks in or not, how air is directed). I hope it is more or less explained in the manual. I would appreciate if somebody shed some light on that.