Purge 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.
If the ambient air temperature is less than 2 C (35 F) and the coolant temperature is less than 10 C (50 F), then a 75-second purge will occur. The purge will begin as soon as the coolant temperature reaches 4 C (40 F). The mode door will move to the defrost position and the blower motor will be near half speed.