Air Handling
All airflow from the blower motor passes through the evaporator core (if equipped). Based on the climate control system temperature settings, the temperature door actuator directs airflow through the heater core as needed. The air distribution door actuator controls the airflow to the defrost, footwell or register vents. The air source is from outside air or recirculated passenger compartment air as determined by the air inlet door position. The cabin air filter is located in the heater core and evaporator core housing. For cabin air filter maintenance intervals, Refer to: MAINTENANCE SCHEDULES - GASOLINE ENGINES .
The air distribution door and temperature door actuators use a potentiometer to sense and communicate the door position to the HVAC control module. When in airflow mode or a desired temperature is requested by the HVAC control module, the appropriate door actuator motor is driven to the desired position, using the position sensed by the door actuator potentiometer to accurately position the door actuator.
The blower motor is controlled using a blower motor resistor. The blower motor resistor uses 3 resistance elements that are wired in series on the ground side of the blower motor. The blower motor has 4 speeds:
- for low speed, all 3 resistors are used
- for medium-low speed, resistors 1 and 2 are used
- for medium-high speed, resistor 1 is used
- for high speed, the blower motor is provided a path directly to ground and the blower motor resistors are not used
The HVAC control module grounds 1 of the 4 circuits to control the blower motor speed.