Control System Outputs

Blower Motor Speed Control 

The A/C blower motor speed control:

• is located on the A/C evaporator housing, in the engine compartment.
• converts low power signals from the dual automatic temperature control module to a high current, variable ground feed for the blower motor.
• varies the blower motor speed and is controlled by the HVAC module software.
• provides a gradual increase or decrease in blower motor speed under all conditions by use of a delay function.

Temperature Blend Door Actuators 

The dual-zone electronic automatic temperature control (EATC) system uses 2 temperature blend door actuators to control 2 separate temperature blend doors. The temperature blend doors independently vary the LH and RH temperature settings. The temperature blend door actuators:

• are located on the heater core housing.
• move the temperature blend doors on command from the HVAC module.
• contain a reversible electric motor and potentiometer. The potentiometer wiper is connected to the actuator output shaft and moves with the output shaft to indicate the position of the temperature blend door.
• receive a 5-volt signal at one end of the potentiometer. The voltage available at the wiper indicates the position of each potentiometer. The expressed value of the actuator wiper voltage is sent to the HVAC module and is matched with an expected wiper voltage value. The control module then drives the actuator motor in the direction necessary to make the actuator wiper voltage match with the expected HVAC module setting.

Mode Door Actuators 

Two electronic mode door actuators are used to position the airflow mode doors. The mode door actuators:

• are located on the plenum chamber.
• each contains a reversible electric motor and potentiometer. The potentiometer wiper is connected to the actuator output shaft and moves with the output shaft to indicate the position of the temperature blend door.
• each receive a 5-volt signal at one end of the potentiometer. The voltage available at the wiper indicates the position of each potentiometer. The expressed value of the actuator wiper voltage is sent to the HVAC module and is matched with an expected wiper voltage value. The control module then drives the actuator motor in the direction necessary to make the actuator wiper voltage match with the expected HVAC module setting.