Heating and Defrosting

Heating And Ventilation:

The heating and defrosting system has the following features:
^ Controls the temperature and, during A/C operation (if equipped), reduces the relative humidity of the air inside the vehicle.
^ Delivers heated or cooled air to maintain the vehicle interior temperature and comfort level.
^ Controls the blower motor speed.
^ Cooling or heating can be adjusted to maintain the desired temperature.
^ System uses a reheat method to provide conditioned air to the passenger compartment.
^ The blower motor draws outside air through the air inlet duct just below the windshield during all system operations except for OFF, MAX A/C (manual systems), or RECIRC (EATC systems), when recirculated air is used.
^ All airflow from the blower motor passes through the A/C evaporator core, if equipped.
^ The temperature is then regulated by reheating a portion of the air and blending it with the remaining cool air to the desired temperature.
^ The temperature blending is varied by the air temperature control door, which regulates the amount of air that flows through and around the heater core, where it is then mixed and distributed.

Heater Core
The heater core consists of fins and tubes arranged to extract heat from the engine coolant and transfer it to air passing through the heater core from the blower motor.

Blower Motor
The A/C blower motor pulls air from the air inlet and forces it into the plenum assembly where it is mixed and distributed. The A/C blower motor has four speeds and is controlled by the blower motor switch and resistor (manual systems) or the EATC module and blower motor speed control (EATC systems).

Heater Control Valve
The heater control valve is actuated by the air inlet door vacuum circuit (manual climate control) or the heater control valve vacuum control circuit (EATC). When the heater control valve is closed (full vacuum), coolant flow through the heater core is shut off and A/C cooling efficiency is increased.