DESCRIPTION
The thermostatic air cleaner is designed to regulate the temperature of incoming air. Non-turbo models use a thermostatic sensor in the throttle housing which activates an air door by cable. Turbo models have an air temperature sensor installed in the air intake to sense ambient air temperature. This sensor activates the air door directly.
NON-TURBO MODELS
When incoming air temperature is below 73°F (23°C), the thermostat positions the air door to allow only heated air to enter the throttle housing. When incoming air temperature exceeds 99°F (37°C), the thermostat opens the door to allow only fresh air. When the temperature is between these extremes, air is mixed from both sources.
TURBO MODELS
Note. Preheater hose must be clamped to boost pressure regulator housing to provide sufficient battery clearance.
Incoming air below 23°F (-5°C) causes the air door to admit air from the exhaust manifold only. The thermostat mixes fresh and heated air up to 41°F (5°C), when the fresh air duct becomes fully open.
TESTING
Note. Thermostat on Turbo cannot be tested in water since the operating temperature of the thermostat is below freezing.
- A rough test can be made by removing air intake and watching valve operation as a cold engine is started and warmed up.
- To accurately test sensor, remove entire unit from vehicle. Immerse sensor in water. Verify that valve is open to fresh air side when water is above 99°F (37°C), and open to heated air side when water is below 73°F (23°C).
Note. When checking sensor, the cable should be in approximately the same position it is when installed on engine.