An air-treatment system for a motor vehicle having an air conditioner, the system has an electrically powered air-treatment device in the air conditioner that treats air of an airflow generated by the air conditioner, a controller in the air conditioner that controls the air-treatment device in accordance with operating parameters of the air conditioner in which the air-treatment device is installed, and an electrical coder in the air-treatment device for identifying characteristics of the air-treatment device, that is electrically connectable with the controller on installation of the air-treatment device, and that is interogable after electrical connection to the controller has been established. This coder serves for detecting when the electrical coding means is electrically connected to the controller and for disconnecting electric power feed to the air-treatment device in the absence of an electrical connection between the coder and the controller.