Air Distribution System

Flow-Through Ventilation System (Typical):

AIR INLET VALVE

The valve allows fresh (outside) air to enter the HVAC module when open. The valve will force the passenger compartment air to be recirculated when the valve is closed. The valve is located on top of the HVAC module at the right-hand front comer of the passenger compartment.

BLOWER AND EVAPORATOR

The blower moves air across the HVAC module case and through the evaporator. The evaporator dehumidifies the air and the resulting moisture is expelled through a drain at the front of dash. The blower speed is controlled by the position of the blower speed switch and dictated by a resistor in the electrical circuit.

TEMPERATURE AIR VALVE AND HEATER VALVE

In all A/C modes, the heater core is used to heat the cool dehumidified air to achieve the desired passenger compartment temperature. The movement of the temperature control knob actuates the temperature valve and determines how much heat will be added to the incoming air. The heater valve is used to direct heated air based on the mode setting. The temperature valve and the heater valve are located in the mid section of the HVAC module, downstream of the evaporator.

MODE AIR VALVE

The mode valve determines the direction of the air mix based on input from the mode switch. The mode valve is vacuum actuated. The mode valve is located in the top of the HVAC module.

DEFROST VALVE

The defrost valve directs the air mix to the windshield based on input from the mode switch. The defrost valve is vacuum actuated. The defrost valve is located in the top of the HVAC module near the front of dash.

DUCTS AND OUTLETS

A system of ducts and outlets directs air from the HVAC module to the passenger compartment. In cases of poor air output, defroster, heater, A/C and vent ducts should be checked for obstructions or other objects which may have fallen into the ducts, air inlet, or cowl panel screen. Vehicles are equipped with side window defoggers. Removal and installation of duct work is covered under "On-Vehicle Service."

VENTILATION

This vehicle has a "flow-through" ventilation system. A supply of outside air flows into the vehicle when the blower motor is running. With the side windows closed, some air will flow into the cowl air inlet grille, through the vehicle and out the pressure relief valves.