A method of controlling an HVAC system (10) that comprises least one flow regulator (16), an electromechanical actuator (20), one or more sensors (34) associated with the actuator, and a controller (32) operatively connected with the actuator and with the sensors. The method includes the steps of actuating the flow regulator, receiving signals from the sensors, and determining an actual or forthcoming malfunction based on the signals. It is determined whether the malfunction is in the actuator or the flow regulator.