Vent Mode
WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
When the vent button is depressed, outside air is brought into the vehicle and the A/C compressor clutch is turned off. The vent button will not effect the HVAC system when the front defrost mode is selected. If the vent button is pressed while system is in front defrost mode, the vent button will flash 3 times to remind the driver that vent mode is not available. When the HVAC system is off, pressing the vent switch will put the HVAC system in automatic mode.