Dual Zone Operation
WARNING: This page is about a different car, the 2003 Buick Regal and 2003 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
The right air temperature switch allows the passenger to offset air discharge temperatures on the right side of the vehicle. To activate the dual zone, the passenger slides the switch to the desired offset. The HVAC control module will position the right air temperature actuator, located on the right side of the HVAC module to a position to divert sufficient air past the heater core to achieve the desired passenger temperature.