Blower Motor Control - Dual Zone Automatic System

Blower motor speed is controlled automatically by the ATC module unless a manual override has been requested. Manual overrides to blower motor speed can be made by turning the central rotary controller to the required position. The rotary controller allows the manual selection of 7 blower motor speeds. Turning the controller fully counter clockwise will turn the blower motor off. When a manual override has been made, the 'AUTO' LED located in the center of the rotary controller will extinguish.

NOTE: The central rotary controller contains 2 LED's. The top (round) LED will illuminate when the blower motor is under automatic control. The bottom (rectangular) LED will illuminated when air distribution into the cabin is under automatic control.

The blower motor can be returned to automatic control by pressing the 'AUTO' switch located in the center of the rotary controller. Under automatic control, the ATC module varies the speed of the blower motor in line with its 'comfort' algorithm to maintain the required cabin temperature. The ATC module will also vary the blower motor speed to compensate for the ram effect on intake air produced by forward movement of the vehicle.

Operation of the blower motor is controlled by the ATC module via the blower motor control module. The ATC module provides a PWM signal to the blower motor control module based on the required blower speed. The blower motor control module interprets the PWM signal as a blower motor speed and controls the voltage to the blower motor accordingly.