Thermostatic Air Cleaner: Operation: Notes

When air cleaner is cold, vacuum motor diaphragm is pulled by intake manifold vacuum and opens the hot air control valve. This allows intake of hot air from a stove on exhaust manifold.

When air cleaner reaches a temperature of 100-111°F (38-44°C), thermo-sensor comes into function and stops supply of vacuum from intake manifold. When vacuum is stopped, hot air control valve opens and permits entry of cool outside air. This holds temperature of intake air at a nearly constant temperature.

As negative pressure in the intake manifold decreases (closing throttle valves) the vacuum motor diaphragm returns to its normal state and permits entry of cool air into the carburetor even when thermo-sensor if out of function.