2002 GMC Envoy Owner's Manual - Page 185

Ventilation System For mild outside temperatures when little heating or cooling is needed, use the panel outlet setting (on the standard system) to direct outside air through your vehicle. Air will flow through the instrument panel outlets. Your vehicle's flow-through ventilation system supplies outside air into the vehicle when it's moving. When the vehicle is not moving, you can get outside air to flow through by selecting any air delivery mode and any fan speed. Your vehicle has air outlets that allow you to adjust the direction and amount of airflow inside the vehicle. Move the outlet up or down and move the control in the center of each outlet side-to-side to direct the air from the outlet. Use the thumbwheel under the outlet to turn the outlet off. For the most efficient airflow and temperature control, keep the outlet in the fully opened position. The rear seat outlets can be used to adjust the airflow toward either seating area, the floor or upward. Move the control in the center of each outlet in any direction to direct airflow. 3-11