Air Cleaner - Thermostatic: Operation: Notes
When the temperature of the air entering the air cleaner is less than the calibrated temperature of the temperature sensor, the sensor closes. This allows engine vacuum to operate the vacuum motor.
When engine vacuum is applied to the vacuum motor, the door closes off outside air. Air is then drawn into the air cleaner from around the exhaust manifold.
As air inside the air cleaner warms, the temperature sensor begins to close. This gradually bleeds off vacuum to the vacuum motor. As vacuum to the vacuum motor decreases, the air control door begins to open.
As the air control door opens, outside air is allowed to enter the air cleaner assembly. When the air entering the air cleaner reaches a predetermined temperature, the air control door opens completely. This completely closes off air from around the exhaust manifold.