A motor control system for controlling operation of an electric motor associated with a motor-operated vent in a vehicle. The system monitors and stores data relating to the operating current and detects occurrences of abnormal loads applied to the vent by determining whether the monitored operating current exceeds one of several predetermined thresholds. The predetermined thresholds are dynamically modified in accordance with monitored condition variations of the operating current. The dynamically modified thresholds are initially based on either a value associated with the stall current of the vent motor or the start spike current of the vent motor. In addition, an embodiment is provided for monitoring and storing data relating to ripple current waves associated with the operating current, so that occurrences of abnormal loads may be detected by determining whether the frequency of the monitored ripple current waves is less than a predetermined value.