Thermostatic Air Cleaner: Operation

When underhood air temperature is below 112°F (44°C), temperature sensor valve is closed. This directs manifold vacuum to air control diaphragm, which opens air control valve. With valve open, pre-heated air flows into air cleaner from heat stove.

When underhood air temperature is 112-133°F (44-56°C), temperature sensor valve is partially open. This reduces vacuum applied on air control diaphragm, and results in a smaller air control valve opening. In this condition, intake air is a blend of direct underhood and pre-heated air.

When underhood air temperature rises above 133°F (56°C), the temperature sensor valve opens fully to cut off all vacuum to air control diaphragm. In this condition, air control valve is closed and only underhood air flows into air cleaner.