1996 GMC Savana Van Owner's Manual - Page 122

To regulate the airflow location, adjust the center knob on the control panel. Turn the knob counterclockwise for floor vent air flow or clockwisefor headliner vent air flow. Generally, the upper vents are used for air conditioning and the floor vents for heating. The control knob can be set to any blend setting. To adjust the air flow speed, turn the fan control knob on the left side of the control panel to the desired blower setting. To activate the rear control, move the fan knob on the front control to REAR CNTL. The rear control works just like the front control. It will allow second seat passengers to adjust the controls as they desire. 3-6