A device for cooling a radiator, including an air guide attached to structural portions of a vehicle and a device having movable air-blocking flaps, the air guide includes at least two separate portions: a front portion and a rear portion, respectively, which include a mechanism for mutual attachment, the rear portion being attached to the structural portions and including a receiving area configured to receive the device having blocking flaps, the entire assembly being held in place by an attachment mechanism of the front portion onto the rear portion.