Air Distribution System

Control of airflow through the HVAC module is regulated by vacuum-actuated doors. Outside air is either cooled or heated and then discharged according to control setting.

In case of vacuum line/harness leakage or hose collapse, it is not necessary to replace the entire vacuum harness assembly. Replacement can be made by cutting the hose and inserting a plastic connector. If an entire hose must be replaced, cut the hose off at the connector and then attach a new hose directly to the vacuum solenoid control assembly.

VACUUM SYSTEM
All air valves except the temperature valve are controlled by engine vacuum stored in the vacuum tank in the engine compartment. The vacuum is routed by a vacuum switch in the control assembly to any of the spring-loaded valves or three-position vacuum actuators. One vacuum actuator is linked to each air valve.

The vacuum switch in the control assembly is controlled by the mode control knob. For each mode control knob position, the vacuum switch directs engine vacuum to specific hoses and vents to normal air pressure the remaining hoses. When a hose vents to normal air pressure, the vacuum actuator's internal spring expands and holds the associated air valve in one position. When vacuum routes to the hose, the force of the vacuum overcomes the internal spring pressure and moves the air valve to the opposite extreme of its travel. In this way, the control knob positions the air 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, defroster, heater, air conditioning, and vent ducts should be checked for obstructions such as leaves, dirt, or objects that may have fallen into the ducts from the passenger compartment.