Abstract: An air vent includes a louver blade mounted in a housing for rotation about an axis. A motor output shaft is connected to a driving link to rotate the driving link about the axis. A driven link in the form of a crank arm extends from the driving link to the louver blade. A spring in the form of a torsional coil spring interconnects the driving link and the driven link for transmitting rotation therebetween to adjust the louver blade. When an undesired external force is applied to the louver blade, the spring can yield elastically to prevent relative movement between the driving link and driven link in order to protect the motor.