Vacuum Test - HVAC System - Automatic

Vacuum Test:

1. Inspect the vacuum supply to the vacuum/electric solenoid (vacuum hose-PPL) while the engine is running. The following conditions need to be met:
^ The vacuum should be approximately 60 kPa (18 psi) with the engine running.
^ The vacuum should remain at approximately 60 kPa (18 psi) when the engine is turned OFF.
2. Test each vacuum actuator by disconnecting the vacuum hose and applying vacuum directly to the actuator. Repair or replace a vacuum actuator as needed.
3. Reconnect all of the vacuum and electrical connections.
4. Run the engine and cycle through the operating modes of the heater-A/C control while observing the valve actuators.
5. Inspect 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 table.

6. If a valve actuator retracts when the actuator should not, replace the vacuum electric solenoid. Refer to Vacuum Electrical Solenoid Replacement.
7. If a valve actuator does not retract when the actuator should, inspect for vacuum leaks, restricted hoses, or binding valves and linkages.