One of the black arrows points up to the defroster vents in the dash, the other black arrow points down to the floor vents. The red arrows are for heat. The amount of heat on the right and left side can be regulated separately. The blue arrow is fresh air to the floor or defroster vents. The colored triangles are meant to indicate open or closed, where the wide end of the triangle indicates fully open or on and the narrow tip of the triangle indicates fully closed or off.
The cryptic label is showing the positions of the four levers to achieve maximum defrosting of the windshield. The fresh air lever (blue) on the upper left left should be all the way to the left (fully open). The air flow lever (black arrows) should on the upper right should be all the way to the left (up arrow, defrost). The heat control lever (red) on the lower left should be all the way to the left (maximum coolant flow and air flow through the heater core for heating the left hand side of the car). The heat control lever (red) on the lower right should be all the way to the right (maximum air flow through the heater core for heating the left side of the car.)
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In the summer, the most effective way to keep the passenger compartment cool would be to keep the fresh air lever (blue) all the way to the left, the air flow lever (black arrows) should be moved all the way to the right (down arrow, floor), and both heat control (red) levers should be moved to the center of the panel (coolant flow to the heater core shut off, and no air flow through the heater core to the vents,).
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The two round vents at each end of the dash are fresh air vents independent of the heater/defroster system. When the lever below each vent is pointing away from the door the vent is closed; when pointing towards the door, the vent is open and air will flow when the vehicle is in forward motion.
