General Information

The purpose of the climate control system is to route air to the designated registers. This is accomplished when air enters the plenum through the fresh/recirculated air inlet and is routed to the desired outlets by the use of distribution doors.

The air distribution system contains the heater core, A/C evaporator core, blower motor and all of the distribution doors. All of the air is mixed and distributed inside of the plenum assembly, depending on the distribution door positions.

Heating/defrosting
The heater system is a blended air system, receiving outside air through the air inlet, which is connected to the upper cowl. Air is directed through the heater core for heating and around for cooling, mixed and discharged through outlets in the plenum assembly to the floor, panel or defrost nozzles, as desired.

Refer Heating and Air Conditioning.

Heater Core
The heater core consists of a number of fins and tubes in an arrangement to extract heat from the engine coolant and transfer that heat to the air that passes through the heater core.

Blower Motor
The blower motor pulls air from the air inlet and forces it into the plenum assembly where it is mixed and distributed. The blower motor has four speeds and is controlled by the blower motor switch and resistor.

Air Conditioning
The R-134a Air Conditioning (A/C) system uses a Hydrofluorocarbon (HFC) (non-CFC) based refrigerant and a special refrigerant oil. Do not use R-12 tools and equipment when repairing an R-134a system unless specified in the workshop manual. Never mix R-12 and R-134a refrigerants and oils. They are not compatible.

A/C System
The A/C system is a multi-piece, single case design, with an integral blower. The system allows the operator to control the temperature by delivering heated or cooled air to maintain a constant vehicle comfort level. In addition, during A/C operation, it reduces the relative humidity of the air inside the vehicle. Controls are provided to adjust the temperature and system functions, including blower motor speeds for desired airflow. Outside air is drawn from the cowl air inlet just below the windshield during all system operations except for MAX A/C cooling (when recirculated air is used) and OFF. Temperature control can be maintained in all control settings except when the system is turned OFF.

Control System Inputs
The climate control system inputs are selected manually from the climate control assembly.

Control System Outputs
The air management doors are controlled by vacuum control actuators and an electronic blend door motor. The air inlet and distribution doors are controlled by vacuum control actuators. The temperature blend door is controlled by the electronic motor.

The electronic blend door motor provides a infinite number of temperature blend door positions. Temperature control position energizes the electronic motor moving the temperature blend door.

Vacuum control actuators are used on both air distribution and air inlet doors. Vacuum control actuators are controlled by the climate control assembly through the engine vacuum.