Stepper Motor Operation: Notes

BMW IHKR and IHKA Climate Control Systems use 12 volt DC electric stepper motors to operate many of the air inlet, air distribution and temperature mixing flaps. While different types of stepper motors are used on different vehicles, they all share many desirable characteristics:

• lower power consumption
• operate in both directions
• can be started and stopped in any position
• provide quick movement
• move in precise increments
• does not require feedback potentiometers to determine position
• remain in position when shut off
• have long service life

Unlike a "normal" 12 volt DC motor (for example, a blower motor) in which the rotor spins through many revolutions per second when the motor receives power a stepper motor rotor rotates through only a small angle when it receives power and then it stops.