Vacuum System - Testing

Air Delivery Vacuum Distribution Table:

NOTE: To avoid misdiagnosis, complete Air Flow From Outlets is Incorrect under Diagnostic Charts before beginning the diagnostic procedure listed below. Air Flow From Outlets Is Incorrect

1. Check vacuum supply to solenoid box (black vacuum hose) while engine is running.

^ Vacuum should be approximately 60 kPa (18 psi) with engine running.

^ Vacuum should remain at approximately 60 kPa (18 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. Run engine and cycle through the operating modes of the heater control assembly while observing the vacuum actuators.

^ Check for vacuum to the vacuum actuators by noting vacuum actuator position. When vacuum is applied, the actuator will retract, refer to the "Air Delivery Vacuum Distribution Table" in the accompanying image.

^ If a vacuum actuator retracts when it should not, replace the heater control assembly.

^ If a vacuum actuator does not retract when it should, check for vacuum leaks, collapsed vacuum hoses or binding valves. If OK, replace the solenoid box.