GM Service Manual Online
For 1990-2009 cars only

Vacuum Electrical Solenoid Description CJ4

The heater-A/C control microprocessor releases electrical signals. The vacuum solenoid module converts electrical signals into vacuum commands. The vacuum commands position the following valves in the air distributor:

    • Mode valve
    • A/C-defrost valve
    • Outside air valves

Vacuum is constantly applied to the module. The module distributes the vacuum to five solenoid-controlled valves on the module. The following actions occur when the heater-A/C control signals the module to change an air distributor valve position:

    • The solenoid that is associated with the valve energizes.
    • Vacuum is applied to the appropriate actuator.