Important: To avoid misdiagnosis, complete Symptoms before beginning vacuum diagnosis.

This air delivery system uses a manual selector located in the heater-A/C control module to operate vacuum controls in the air distribution ducts.

1. Check the vacuum supply to the vacuum selector (purple and black vacuum hoses) while the engine is running.

•	Vacuum should be approximately 40 kPa (6 psi) with engine running.

•	Vacuum should remain at approximately 40 kPa (6 psi) when engine is turned OFF.

2. Test each vacuum actuator by disconnecting the vacuum hose and applying vacuum directly to the actuator. Repair or replace as necessary.
3. Reconnect all vacuum and electrical connections. Start the engine and cycle through the operating modes of the heater-A/C control while observing the valve actuators.

•	Check for vacuum to the mode valve actuators by noting the mode valve actuator position. When vacuum is applied, the actuator will retract, refer to the Air Delivery Vacuum Distribution table.

•	If a vacuum actuator retracts when it should not, replace the heater-A/C control module assembly. Refer to Control Assembly Replacement .

•	If a vacuum actuator does not retract when it should, check for vacuum leaks, collapsed vacuum hoses or binding valves. If these are OK, replace the affected vacuum actuator.