Thermostatic Air Cleaner (ACL)

Used only on TBI engines, this system controls incoming air temperature to throttle body when ambient temperature is low. Heated air allows leaner throttle body calibration, provides better cold driveability and minimizes throttle body icing.

When ambient temperature is at least 15°F (9°C) greater than control temperature, airflow will be through outside outlet. When ambient temperature is less than control temperature, air flows through both air inlets after engine has been started.

With a colder ambient temperature, more air flows past exhaust manifold to heat incoming air. With a warmer ambient temperature, more air flows through air cleaner snorkel, by-passing exhaust manifold.

Temperature of incoming air charge is controlled by intake manifold vacuum, temperature sensor (inside air cleaner assembly) and a vacuum diaphragm which operates door inside air cleaner snorkel.

Vacuum diaphragm is opposed by a spring which closes air door when vacuum signal is removed. Temperature control occurs during road load conditions or when intake manifold vacuum is above operating vacuum of vacuum diaphragm.