There is also front defrost. The car turns on AC automatically if in defrost mode to get the moisture out of the air. It also blows the air through the vents right underneath the windshield for max effect.
1. Turn on front defrost
2. Turn fan speed to min and heater setting to max
3. Once car is warmed up, turn fan speed up to medium or high
4. Once all windows are clear, switch from front defrost to heater only