Bi-Level Mode

WARNING: This page is about a different car, the 2003 GMC Safari and 2003 Chevrolet Astro. However, it is still accessible from the selected car via links, so may be relevant.

When the operator selects Bi-Level, the following occurs:

The mode actuator is in neutral position.
The defrost actuator has vacuum applied to it through the Blue vacuum line.
The defrost actuator closes the defrost door, thus opening the heater door though a mechanical linkage.
Vacuum is bled off the mode actuator and the vent door is held stationary in the half open position.
A/C is forced ON.