A motor control system for use in heating, ventilation, and air conditioning applications includes a blower, a motor coupled to drive the blower, an inverter coupled to provide energization to the motor, and a controller coupled to the inverter. The lift of the actuating element of the actuator is a function of a fluid volume present in the working chamber. A laser diode is energised by a pulsating electric current delivered by a battery powered energising circuit, and the energised laser diode emits light towards the reflecting surface to produce a light spot by direct imaging of the laser diode on the surface.