Distribution

DISTRIBUTION

BLEND AIR MODULE
The blend door actuator is a reversible, 12 volt Direct Current (DC), servo motor.

The blend door actuator is interchangeable with actuators for the mode door and the recirculation air door. Each actuator is contained within an identical black molded plastic housing with an integral wire connector receptacle. Two integral mounting tabs allow the actuator to be secured with two screws to the Heater-A/C unit housing. Each actuator also has an identical output shaft with splines that connects it to the linkage that drives the blend air door. The blend door actuator does not require mechanical indexing to the blend door linkage, as it is electronically calibrated by the Heater-A/C control module.

The blend door actuator cannot be adjusted or repaired and if damaged or faulty it must be replaced.

BLOWER MOTOR RELAY
The blower motor and blower wheel are located in the passenger side end of the Heater-A/C housing, below the glove box. The blower motor controls the velocity of air flowing through the Heater-A/C housing by spinning a squirrel cage-type blower wheel within the housing at the selected speed.

The blower motor will only operate when the ignition switch is in the ON position, and the Heater-A/C blower control switch knob is in any position, except OFF. The blower motor receives a fused battery feed through the blower motor relay whenever the ignition switch is in the ON position.

The blower motor battery feed circuit is protected by a fuse in the Power Distribution Center (PDC). The blower motor control circuit is protected by a fuse in the junction block. Blower motor speed is controlled by regulating the ground path through the Heater-A/C mode control switch, the blower motor switch, the blower motor resistor.

The blower motor and blower motor wheel cannot be repaired and, if faulty or damaged, they must be replaced. The blower motor and blower wheel are each serviced separately

HVAC HOUSING
All vehicles are equipped with a common Heater-A/C housing assembly The system combines air conditioning, heating and ventilating capabilities in a single unit housing mounted under the instrument panel.

Outside fresh air enters the vehicle through the cowl top opening at the base of the windshield, and passes through a plenum chamber to the Heater-A/C system blower housing. Air flow velocity can then be adjusted with the blower motor speed selector switch on the Heater-A/C control panel. The air intake openings must be kept free of snow, ice, leaves, and other obstructions for the Heater-A/C system to receive a sufficient volume of outside air.

It is also important to keep the air intake openings clear of debris because leaf particles and other debris that are small enough to pass through the cowl plenum screen can accumulate within the Heater-A/C housing. The closed, warm, damp and dark environment created within the Heater-A/C housing is ideal for the growth of certain molds, mildews and other fungi. Any accumulation of decaying plant matter provides an additional food source for fungal spores, which enter the housing with the fresh air. Excess debris, as well as objectionable odors created by decaying plant matter and growing fungi can be discharged into the passenger compartment during Heater-A/C system operation.

The heater and optional air conditioner are blend- air type systems. In a blend-air system, a blend-air door controls the amount of unconditioned air (or cooled air from the evaporator on models with air conditioning) that is allowed to flow through, or around, the heater core. A temperature control knob on the Heater-A/C control panel determines the discharge air temperature. By moving a electric actuator which operates the blend-air door. This allows an almost immediate manual control of the output air temperature of the system.

The mode control knob on the heater-only or Heater-A/C control panel is used to direct the conditioned air to the selected system outlets. The mode control switches use an electric actuator to control the mode doors.

The optional air conditioner for all models is designed for the use of non-CFC, R-134a refrigerant. The air conditioning system has an evaporator to cool and dehumidify the incoming air prior to blending it with the heated air. This air conditioning system uses a fixed orifice tube in the liquid line between the condenser and the evaporator coil to meter refrigerant flow to the evaporator coil.

MODE DOOR
There are four mode doors one defrost/demist door, one floor door and two panel doors. All mode doors are driven by one mode actuator that is attached to a mode cam. Each panel door is driven via a linkage to the panel door shaft. The panel door shaft is connected to two panel levers that are interconnected and driven by the mode cam. The floor door is driven by a floor door shaft that is attached to a lever that is driven by the mode cam. The defrost door has a lever that is connected to the mode cam with a linkage. All mode doors are serviced as part of the HVAC housing and are not available as separate components.