Control for dual stepper motors

In an air handling unit for discharging a flow of air into the surrounding ambient, having a series of horizontal louvers and a series of vertical louvers mounted in the discharge flow. A first multi-phase stepper motor is arranged to step the horizontal louvers to deflect the air flow in a vertical direction and a second multi-phase stepper motor is arranged to step vertical louvers to deflect the flow in a transverse direction. A controller is programmed to alternately apply power from a single power source to each of the motors during each phase to step each motor in equal increments during each phase.