Front HVAC Housing

DESCRIPTION





All models are equipped with a common HVAC housing assembly that combines A/C and heating capabilities into a single unit mounted within the passenger compartment. The HVAC housing assembly consists of three separate housings:

- Air inlet housing (1) - The air inlet housing is mounted to the passenger side end of the HVAC housing and contains the recirculation-air door and actuator.
- HVAC housing (2) - The HVAC housing is mounted behind the instrument panel and contains the A/C evaporator, blower motor resistor block or power model (depending on application) and the blower motor. The HVAC housing consists of a upper and a lower housing that are attached together and has mounting provisions for the air inlet housing and air distribution housing.
- Air distribution housing (3) - The air distribution housing is mounted to the rear of the HVAC housing and contains the heater core, blend-air doors and actuators, mode-air doors and actuator, door linkages and the evaporator temperature sensor. When the vehicle is equipped with the 3.0L diesel engine, the air distribution housing also contains the electric Positive Temperature Coefficient (PTC) heater unit.

The heating-A/C system is a blend-air type system. The blend-air doors control the amount of conditioned air that is allowed to flow through, or around the heater core. The two available dual zone heating A/C systems use two blend door actuators.

The A/C system is designed for the use of a non-CFC, R-134a refrigerant and uses an A/C evaporator to cool and dehumidify the incoming air prior to blending it with the heated air. A temperature control determines the discharge air temperature by operating the blend door actuators, which moves the blend-air doors. This allows an almost immediate control of the output air temperature of the system. The two mode door actuators operate the mode-air doors which direct the flow of the conditioned air out the various air outlets, depending on the mode selected. The recirculation door actuator operates the recirculation-air door which closes off the fresh air intake and recirculates the air already inside the vehicle. The blower motor controls the velocity of air flowing through the HVAC housing assembly by spinning the blower wheel within the HVAC housing at the selected speed by use of a blower motor resistor or power model, depending on heater-A/C system application.

The HVAC housing must be removed from the vehicle and disassembled for service of the A/C evaporator. The air distribution housing must be removed from the HVAC housing and disassembled for service of the mode-air and blend-air doors. The air inlet housing must be removed from HVAC housing and disassembled for service of the recirculation-air door.