Air Distribution System

The air distribution system utilizes a series of valves to control airflow through the ducts. There are three actuators in the series the temperature valve actuator, air inlet actuator, and the defroster valve actuator. Valves are hinged parts that act like doors to direct airflow through various sections of the heater module and provide the proper airflow for the selected operating mode.

In case of vacuum line/harness leakage or hose collapse, it is not necessary to replace the entire vacuum harness. Replacement can be made by cutting the hose and inserting a plastic connector.

Vacuum System

All valves are controlled by engine vacuum stored in the vacuum tank in the engine compartment. Vacuum is routed by a vacuum switch in the control assembly to either of the spring-loaded three-position vacuum actuators.

The mode knob controls the vacuum switch. For each mode knob position, the vacuum switch will direct engine vacuum to specific hoses and vent the remaining hoses. When a hose is vented to normal air pressure, the vacuum actuators internal spring will expand and hold the associated valve in one position. When vacuum is routed to the hose, the force of the vacuum overcomes the internal spring pressure and moves the valve to another position. In this way, the mode knob positions the valves for the selected operating mode.

Ducts And Outlets

A system of ducts and outlets directs air to the passenger compartment. In cases of poor air output the ducts should be checked for obstructions such as leaves, dirt, or objects that may have fallen into the ducts from the passenger compartment.