Device and method of mounting a heat exchanger, particularly for vehicles

The equipment for installing a heat exchanger in a casing (10) delimited by walls (18,19,20,22) comprises an adapter part (50) which is interposed between the heat exchanger and the casing walls in order to compensate for a dimensional difference with another exchanger. The adaptor part comprises a rectangular frame with two lateral faces (52,54) joined by two crosspieces (56,58). Heat exchangers of a first or second type (36) can thus be placed in the same casing. An Independent claim is included for a method of installing the heat exchanger in a casing.