Air Cleaner - Thermostatic: Description
During cold engine operation most passenger cars preheat the air entering the carburetor or the fuel injection unit. This system maintains incoming air temperature to a point where the carburetor or fuel injection system can be kept lean to reduce hydrocarbon (HC) emissions, and reduce carburetor icing.
Most passenger cars are equipped with dry type air cleaners with a replaceable air filter element. These air inlet systems have various sensors, switches and vacuum motors to control inlet air temperature. There are also various sensors present in the air cleaner for other engine control systems.