Thermostatic Air Cleaner: Description and Operation

Heated Inlet Air System:

This system uses a thermostatically controlled air cleaner to maintain a predetermined air temperature entering the throttle body when underhood temperatures are less than 100° F. By maintaining this temperature, the throttle body can be calibrated leaner, improve engine warm-up and minimize throttle body icing. Temperature is controlled by intake manifold vacuum, a temperature sensor, and a vacuum diaphragm which operates the heat control door in the air cleaner snorkel.

During engine warm-up air is heated by a shroud surrounding the exhaust manifold, then the air is piped to the air cleaner snorkel and into the throttle body. The vacuum diaphragm controls the air control valve which is closed to outside air. Therefore all air entering the throttle body is heated.

During normal operation, as the air entering the air cleaner increases, the air control valve opens to allow heated air to mix with cold air to keep the air entering the throttle body at about 100° F.

During wide-open throttle operation, or at any time engine vacuum is below 4-6 inches Hg, the hot air duct is closed off allowing only cold air to enter the throttle body.