A multiple bank, flattened tube heat exchange unit includes a first tube bank including a plurality of flattened tube segments extending longitudinally in spaced parallel relationship between a first manifold and a second manifold and a second tube bank including a plurality of flattened tube segments extending longitudinally in spaced parallel relationship between a first manifold and a second manifold, the second tube bank disposed behind the first tube bank. The second manifold of the first tube bank and the second manifold of the second tube bank form a manifold assembly wherein an interior volume of the second manifold of the first tube bank and an interior volume of the second manifold of the second tube bank of the manifold assembly are internally connected in fluid communication.