Device for assembling a motor-fan unit to a radiator of a motor vehicle, the assembly device comprising: - a first peripheral support frame intended to support the motor-fan unit and a second peripheral support frame intended to support the radiator, at least one of the support frames being fitted with at least one peripheral sealing baffle intended to overlap the lateral peripheral edge of the other support frame, - at least two upper fixing points and at least two lower fixing points integral to each of said support frames (9, 11), characterized in that each fixing point (19a, 19b) comprises a pin (19a1, 19b1) and a lug (19a2, 19b2) defining a housing and arranged to cooperate by engaging together simultaneously, the pins (19a1, 19b1) of the fixing points being integral with one support frame and the corresponding lugs (19a2, 19b2) being integral with the other support frame, and wherein each lug (19a2) of an upper fixing point defines a U-shaped housing with the support frame with which it is integral, and the corresponding pin (19a1) is shaped to slide in this U-shaped housing, the pins (19a1) and lugs (19a2) of the upper fixing points being positioned and arranged such that when the pins (19a1) are inserted in the U-shaped housings, the upper parts of the support frames (9, 11) are held at a predefined distance from each other in a direction perpendicular to the plane of the support frames (9, 11), and each lug (19b2) of a lower fixing point is L-shaped and defines an L-shaped housing with the support frame with which it is integral, the opening of this housing being located at one end of the main branch of the L-shaped lug (19b2) and the base of this housing being located at the other end of the lug (19b2) integral with the support frame, and the corresponding pin (19b1) is shaped to slide in this L-shaped housing, the pins (19b1) and lugs (19b2) of the lower fixing points being positioned and arranged such that when the pins (19b1) are inserted in the main branch of the L-shaped housing, the lower parts of the support frames (9, 11) are held spaced apart, and when the pins (19b1) are inserted into the base of the lower branch of the L-shaped housing, the lower parts of the support frames (9, 11) are held at a predefined distance from each other in a direction perpendicular to the plane of the support frames (9, 11), and in that the assembly device further comprises: - at least one lateral indexing element able to position the support frames (9, 11) in relation to each other in a direction parallel to the plane of the support frames (9, 11) and perpendicular to the sliding direction of the pins (19a1) in the U-shaped housings, and - at least one element for locking the assembly of support frames (9, 11) in relation to each other. - a first peripheral support frame intended to support the motor-fan unit and a second peripheral support frame intended to support the radiator, at least one of the support frames being fitted with at least one peripheral sealing baffle intended to overlap the lateral peripheral edge of the other support frame, - at least two upper fixing points and at least two lower fixing points integral to each of said support frames (9, 11), characterized in that each fixing point (19a, 19b) comprises a pin (19a1, 19b1) and a lug (19a2, 19b2) defining a housing and arranged to cooperate by engaging together simultaneously, the pins (19a1, 19b1) of the fixing points being integral with one support frame and the corresponding lugs (19a2, 19b2) being integral with the other support frame, and wherein each lug (19a2) of an upper fixing point defines a U-shaped housing with the support frame with which it is integral, and the corresponding pin (19a1) is shaped to slide in this U-shaped housing, the pins (19a1) and lugs (19a2) of the upper fixing points being positioned and arranged such that when the pins (19a1) are inserted in the U-shaped housings, the upper parts of the support frames (9, 11) are held at a predefined distance from each other in a direction perpendicular to the plane of the support frames (9, 11), and each lug (19b2) of a lower fixing point is L-shaped and defines an L-shaped housing with the support frame with which it is integral, the opening of this housing being located at one end of the main branch of the L-shaped lug (19b2) and the base of this housing being located at the other end of the lug (19b2) integral with the support frame, and the corresponding pin (19b1) is shaped to slide in this L-shaped housing, the pins (19b1) and lugs (19b2) of the lower fixing points being positioned and arranged such that when the pins (19b1) are inserted in the main branch of the L-shaped housing, the lower parts of the support frames (9, 11) are held spaced apart, and when the pins (19b1) are inserted into the base of the lower branch of the L-shaped housing, the lower parts of the support frames (9, 11) are held at a predefined distance from each other in a direction perpendicular to the plane of the support frames (9, 11), and in that the assembly device further comprises: - at least one lateral indexing element able to position the support frames (9, 11) in relation to each other in a direction parallel to the plane of the support frames (9, 11) and perpendicular to the sliding direction of the pins (19a1) in the U-shaped housings, and - at least one element for locking the assembly of support frames (9, 11) in relation to each other.