2003 GMC Yukon Owner's Manual - Page 187

To operate the rear system using the front control, just turn the knob to the fan position you want. Rear Air Conditioning and Heating System If your vehicle is equipped with this system, there are two rear heat and air conditioning controls. One control is located in the overhead console and the other is located in the headliner above the second row seats. The system can be controlled from the front controls as well as the rear controls. Rear Control To use the rear control, first turn the front control to the AUX position. Then, the rear control can be used to increase and decrease the airflow. Front Control The front control has three knobs that control airflow speed, temperature and airflow location. 3-33