Dodge 2005 Grand Caravan - Manual (Page 276)

Bi-Level Mode Air comes from both the instrument panel outlets, floor
outlets and defrost. A slight amount of air is also directed
through the side window demister outlets.
NOTE: In many temperature positions, the bi-level
mode is designed to provide cooler air out of the panel
outlets and warmer air from the floor outlets.
Bi-Level Outlets
276 UNDERSTANDING YOUR INSTRUMENT PANEL