Box for receiving a fluid for a heat exchanger and method of producing such a casing, heat exchanger

The invention relates to a box for containing a coolant for a heat exchanger (1) for motor vehicles, with two side walls (22, 24 or 22a, 24a), two end walls (26, 28 or 26a, 28a), a cover (18 or . 18a) and oppositely arranged one (the cover 18, 18a) of the base (20 or 20a) in which one or more openings (60) for receiving tubes, in particular connecting pipes, such as flat tubes, are provided, wherein the bottom ( 20 or 20a) and at least one (of the two end walls 26, 28 or 26a, 28a) are a one-piece, formed by a molding process molding.