Abstract: A heat exchanger is provided with pivotally mounted, angularly disposed, cooling modules or cores so as to increase the cooling capacity of the heat exchanger and, at the same time, to have a self-cleaning capability for the modules or cores. The angular disposition of the modules or cores results in a larger effective frontal area to the heat exchanger thereby increasing the cooling capacity of the heat exchanger. The angular orientation of adjacent modules or cores slightly compresses the oncoming air which provides an increased level of cooling for the cores. Each module or core can be pivoted about an axis a sufficient amount such that the opposite surface of each module or core is swept by the oncoming air which passes around and through the modules or cores in a direction opposite to an initial pass of said air whereby the modules or cores are cleaned by the reverse flow of air.