Front Defrost
WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2002 GMC Yukon XL, 2002 GMC Yukon, 2002 Chevrolet Tahoe, 2002 Chevrolet Suburban, and 2002 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
When DEFROST is selected, the A/C compressor is activated. The A/C compressor clutch will engage when ambient temperatures are above 38°F (3°C). The blower motor will be activated, regardless of the coolant temperature. The HVAC control assembly will override the auxiliary HVAC control assembly so a high volume of air is delivered to the front defrost vents. The rear window defogger does not affect the HVAC system.