The Electronic Climate Control (ECC) Module (Control Assembly) provides a ground for each of the five solenoids in the HVAC Vacuum Control Solenoid Valve (Vacuum Electrical Solenoid). When a ground is provided by the ECC Module a solenoid is energized. The energized solenoid supplies engine vacuum to the associated vacuum actuator. The ECC Module determines which solenoid(s) to energize based on inputs from temperature sensors in AUTO mode or based on the position of the mode knob. The following valves are controlled by vacuum actuators:

Vacuum is constantly applied to the HVAC Vacuum Control Solenoid Valve by a vacuum tank. The HVAC Vacuum Control Solenoid Valve distributes the vacuum to five solenoid-controlled valves. The following actions occur when the ECC Module senses an air valve position needs to be changed: