Housing Assembly HVAC: Description and Operation

DESCRIPTION

NOTE: LHD model shown RHD model similar.





All models use a common HVAC housing assembly. The HVAC housing assembly is mounted within the passenger compartment and consists of three separate housings:

- HVAC housing - The HVAC housing (1) is mounted to the dash panel behind the instrument panel and contains the A/C evaporator, when equipped with A/C. The HVAC housing consists of an upper and a lower housing that are attached together and has mounting provisions for the air inlet housing, air distribution housing, blower motor and blower motor resistor or power module (depending on application).
- Air distribution housing - The air distribution housing (2) is mounted to the rear of the HVAC housing and contains the heater core, blend-air and mode-air doors and door linkage.
- Air inlet housing - The air inlet housing (3) is mounted to the passenger side end of the HVAC housing. When equipped with A/C, the air inlet housing contains the recirculation-air door and recirculation door actuator.

The heating-A/C system is a blend-air type system. The blend-air door controls the amount of conditioned air that is allowed to flow through, or around, the heater core.

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. The discharge air temperature is controlled by an electric blend door actuator, which moves the blend-air door. This allows an almost immediate control of the output air temperature of the system. The electric mode door actuator operates the mode-air doors, which direct the flow of the conditioned air out the various air outlets, depending on the mode selected. 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 module (depending on application). When equipped with A/C, an electric recirculation door actuator operates the recirculation-air door, which closes off the fresh air intake and recirculates the air already inside the vehicle. The electric door actuators, blower motor resistor or power module (depending on application) and the blower motor are connected to the vehicle electrical system by the instrument panel wire harness.

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