1994 GMC Suburban Owner's Manual - Page 141

Air Vents If your vehicle does not have air conditioning,there are air vents below the instrument panel. Use the handles below your steering wheel, with the vent symbols on them, to open and close the vents. If your vehicle has air conditioning, you will find airvents in the center andon the sides of your instrument panel. You can move the vents grilles from side side orup and down to direct to the flow of air, or closethe vents altogether. will of When you close a vent, it increase theflow of air coming out any vents that are open. 3-3