Thermostatic Air Cleaner: Testing and Inspection

1. Visually inspect vacuum hose air cleaner and vacuum operated door for damage and wear, and repair or replace as needed.

2. Remove air cleaner cover and cold air duct, if equipped, then cool thermovalve as needed to simulate cold engine operation.

3. Start engine and ensure that door closes off cold air duct to air cleaner.

4. Install air cleaner cover and warm engine. As engine warms, door should open cold air duct and block hot air duct to air cleaner.

5. If air door fails to operate, connect manifold vacuum directly to vacuum motor.

6. If door operates, replace thermo sensor. If door fails to operate with direct vacuum, replace vacuum diaphragm or repair door as needed.