Auxiliary Blower Motor Speed Control
WARNING: This page is about a different car, the 2017 Lincoln Navigator and 2017 Ford Expedition. However, it is still accessible from the selected car via links, so may be relevant.
The auxiliary blower motor speed control uses a PWM signal from the HVAC control module to determine the desired blower speed and varies the ground feed for the blower motor to control the speed. A delay function provides a gradual increase or decrease in blower motor speed under all conditions.