1997 GMC Suburban Owner's Manual - Page 156

Rear Air Conditioning and Rear Heater (If Equipped) If your vehicle has the rear air conditioning and rear heater system combination, controls are provided to regulate temperature, location and speed of the airflow. For warmer air, turn the knob clockwise toward the red, and for cooler air, turn the knob counterclockwise. To regulate the airflow location, adjust the center knob on the control panel. Turn the knob clockwise for floor vent airflow or counterclockwise forheadliner vent airflow. 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 airflow 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. To adjust the air temperature, turn the temperature knob on the right of the control panel. 3-6