Basically the levers are off when to the center, open when to the outside.
Blue lever opens the air flap at the outside air scoop, this also feeds fresh air to the chrome vents on the outside ends of the dash,
the left red lever opens the hot water valve and controls a hot/cool air mixing flap. Hot to the outside cool to the center.
the right side is only a mixing flap, also cool to the center hot to the outside.
the grey lever is the floor/windscreen control. To the center for defrosting to the outside directs the air to the floor.