Air Handling

WARNING: This page is about a different car, the 2016 Lincoln MKS. However, it is still accessible from the selected car via links, so may be relevant.

There are 4 door actuators that control the air flow into the passenger compartment :

Defrost/panel/floor
Air inlet
LH temperature
RH temperature

All of the door actuators contain a reversible electric motor and a potentiometer. The potentiometer circuit consists of a 5-volt reference signal connected to one end of a variable resistor, and a signal ground connected to the other. A signal circuit is connected to a contact wiper, which is driven along the variable resistor by the actuator shaft. The signal to the HVAC control module from the contact wiper indicates the position of the actuator door. The HVAC control module powers the actuator motors to move the doors to the desired positions. The desired door positions are calculated by the HVAC control module based on the set temperature, in-vehicle temperature, ambient air temperature and sunload.

The HVAC control module sends a PWM signal to the blower motor speed control to regulate the blower speed as necessary. The blower motor speed control provides variable ground feed for the blower motor based on the input from the HVAC control module. A delay function provides a gradual increase or decrease in blower motor speed under all conditions.

All airflow from the blower motor passes through the evaporator core. Based on the climate control system temperature settings, the temperature door actuator directs airflow through the heater core as needed. The defrost/panel/floor mode 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.