Thermostatic Air Cleaner: Description and Operation

HAI System Schematic And Operations Chart:

This system uses hot air from the exhaust manifold to preheat the carburetor intake air supply. This prevents the carburetor from icing and improves drivability in cold weather. Fuel atomization is also improved, thus allowing more complete combustion and lower CO levels. The HAI system consists of the air cleaner housing, preheat hose, the HAI air control valve and hot idle compensation (HIC) valve. When the temperature in the air cleaner is below 79°F, the air control valve is closed, allowing intake air to be preheated from the exhaust manifold. When the temperature in the air cleaner is above 93°F, the air control valve opens, allowing only cool intake air to enter the engine.