Exhaust Emissions System - Thermostatic Air Cleaners: Operation

When the engine is cold, the thermostat in the snorkel senses the low air temperature and closes the air door to prevent entry of cold, outside air. At this point, only heated air from around the manifold shroud enters the carburetor. As the thermostat senses warmer temperatures, it begins to close off the air door to the heated air and allow outside air into the carburetor. In this manner, the temperature of incoming air can be controlled.