Intake Air Temperature Control System

SYSTEM FUNCTIONAL CHECK

1. Remove air cleaner assembly from engine and allow to cool to ambient temperature.
2. After cooling, observe position of air valve. It should be fully open to outside air.
3. Install air cleaner assembly and reconnect hot air hose and vacuum line, then start engine and observe position of air valve. It should be fully closed to outside air.
4. Move throttle rapidly to 1/2 to 3/4 opening and release. Air valve should open and then close again.
5. After engine has reached operating temperature, the air valve should be open to outside air. If air valve does not close at room temperature with vacuum applied, check for a mechanical bind in the snorkel, vacuum motor linkage disconnected, vacuum leaks in hoses or connections at vacuum motor, thermal sensor or intake manifold. If air valve mechanism operates freely and no vacuum leaks are detected, connect a hose from intake manifold vacuum to vacuum motor. If air valve now closes, the thermal sensor is defective. If air valve does not close, vacuum motor is defective.

REVERSE DELAY VALVE
Disconnect vacuum hose from red end of valve and apply an external vacuum source of 2-4 inches Hg, noting time required for vacuum to drop to zero. Replace valve if time is not within 4.5 to 13.2 seconds.