A ventilating system, especially for a motor vehicle air conditioning system, comprises: a wall (4) for mounting an axial fan (2), the latter being equipped with a ring-shaped casing (6), with an axis (X), defined externally by a cylindrical wall (7); an electric motor (11) supported by a plurality of radial spokes (10) connected to the ring-shaped casing (6) and having an impeller (12) at the end of its output shaft; a power cable (14) connected at one end to the motor (11) and connectable at the other end to an electrical power source through a connector (14a). The axial fan (2) is mounted on the wall (4), which delimits a space (5) for containing the air conditioning system, at an air opening (3), in such a way that the impeller (12) faces the inside of the space (5) and the motor (11) faces the outside. The ring-shaped casing (6) comprises means (19) for fastening the cable (14) to its cylindrical outside surface (18) and defining a passage (25) for the cable (14) through the mounting wall (4).