In the fin 112 on the front grille side which is an upstream side of the
air current, there is provided a reinforcing portion 112c formed
when the fin 112 is made into a wave-shape. By this reinforcing portion
112c, it is possible to prevent the core portion 110 (fin
112) from being deformed by water at high pressure. Therefore, it is possible
to reduce the thickness of the fin 112 while the deformation of the fin
112 is prevented even if washing is conducted with water at high pressure.
