Electronic Climate Control

Vacuum System Diagnosis

To test the EATC vacuum system, start the engine and depress the function buttons slowly, one at a time. A momentary hiss should be heard as each button is depressed from one position to another, indicating that vacuum is available at the control assembly. A continuous hiss at the control assembly indicates a major leak somewhere in the system. It does not necessarily indicate that the leak is at the control assembly.

If a momentary hiss cannot be heard as each function button is depressed from one position to another, check for a kinked, pinched, or disconnected vacuum supply hose. Also, inspect the check valve between the intake manifold and the reservoir to ensure it is working properly.