DESCRIPTION
All carbureted models are equipped with a Thermostatic Air Cleaner. It is equipped with an air control valve inside the snorkel which allows either heated exhaust shroud air or cooler ambient air into the carburetor, depending on valve position.
On all models, a vacuum motor which responds to a bi-metallic sensor (located inside air cleaner housing) controls valve position.
OPERATION
When incoming air temperature is below predetermined temperature, air control valve will be in up (hot air only) position. When temperature has reached a predetermined temperature, valve will be in down (cold air only) position. At in-between temperatures, control valve is positioned to blend both hot and cold air. When system operates properly, air temperature is kept constant.
| Application | Valve Up °F (°C) | Valve Down °F (°C) |
|---|---|---|
| All Models | 84 (29) | 113 (45) |
AIR CONTROL VALVE TEMPERATURE SETTINGS
COMPONENT TESTING
- Make sure all vacuum hoses and heat cowl to air cleaner air duct are properly attached and in good condition. With engine cold and ambient temperature less than 84°F (29°C), the air control valve should be in up (heat on) position.
- With engine at normal operating temperature, check air temperature entering outer end of snorkel. When air entering snorkel is 113°F (45°C) or higher, valve should be in down (heat off) position.
- Remove air cleaner from engine and allow to cool to 84°F (30°C). With 15 in. Hg vacuum applied to sensor, valve should be in up (heat on) position. If valve door does not move to up (heat on) position, check vacuum motor for proper operation.
- To test vacuum motor, apply 10 in. Hg vacuum with vacuum pump. Valve should be in full up position. If vacuum motor is not okay, replace air cleaner assembly.
