Air Distribution: Notes
WARNING: This page is about a different car, the 2002 Cadillac Eldorado. However, it is still accessible from the selected car via links, so may be relevant.
When the mode switch is pressed, a signal is sent from the HVAC control processor to the vacuum control assembly. The HVAC control processor will provide ground for the necessary mode actuator solenoid, connecting the desired mode actuator to vacuum. The HVAC control processor provides power to the vacuum control assembly through the vacuum control assembly supply voltage circuit. Ground is provided by the HVAC control module.