Abstract: A heat exchanger assembly comprises a heat exchanger, having a tubular header, and a support member to which the heat exchanger is secured by a fastening device. The heat exchanger is typically a condenser of a motor vehicle air conditioning system. The fastening device comprises a first fastening element having a concave central portion, at least one retaining lug and an extension which is provided with gripping means; a second fastening element having a concave central portion, a retaining lug having at least one aperture for receiving the retaining lug of the first fastening element, and an extension having further gripping means which cooperate with the gripping means of the first fastening element; and a fastening lug which is integral with either the first or second fastening element and which is adapted to be fastened to the support member.