Heating and Ventilation

HEATING AND VENTILATION

The heating and ventilation system:
- controls the vehicle air temperature and, during A/C operation, reduces the relative humidity of the air inside the vehicle.
- delivers heated or cooled air to maintain the vehicle interior temperature and comfort level.
- allows temperature to be adjusted individually by the driver and the passenger to maintain comfort.
- uses a reheat method to provide conditioned air to the passenger compartment. All airflow from the blower motor passes through the A/C evaporator core and the heater core. Temperature is regulated by reheating the air out of the evaporator core to achieve the desired temperature.
- controls the air temperature by regulating the flow of engine coolant to separate halves of the heater core. A dual solenoid actuated valve is used to control the flow of coolant.

The blower motor draws outside air through the air inlet filter and duct or draws recirculated air through the recirculated air duct.

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. The heater core is separated into two sections. Air passing through one section is directed to the driver side of the vehicle, while air passing through the other section is directed to the passenger side of the vehicle. The heater core has separate inlet ports with a common outlet port.

Blower Motor
The A/C blower motor pulls air from the air inlet and forces it into the evaporator housing and plenum assembly where it is distributed.

Dual Coolant Control Valve
The dual coolant control valve regulates the flow of engine coolant to each half of the heater core. Two electric solenoids, which are individually actuated by the dual-zone EATC module, are the control elements. Based on inputs from the dual-zone EATC module, the solenoids cycle open and closed to regulate the coolant flow to the heater core. The solenoids can be cycled at different speeds by the dual-zone EATC module in order to maintain different temperatures for each half of the heater core. Under certain conditions when heating is not required, the dual coolant flow valve will bypass the heater core by closing both solenoids.

Auxiliary Water Pump
Vehicles equipped with a 3.9L engine are equipped with an auxiliary water pump. The auxiliary water pump is electrically driven and provides increased coolant flow during low engine speed operation. The pump is also used to circulate coolant after the engine is turned off under certain conditions.