Abstract: A refrigeration evaporator includes a serpentine refrigerant tube having a plurality of finned straight portions connected by unfinned U-shaped connecting portions to form a stacked assembly of side-by-side finned tube arrays. The fins are rectangular and are provided with a J-shaped cut-out at each corner. The J-shaped cut-outs at confronting corners of the fins of each immediately adjacent pair of finned tube arrays define a U-shaped heater receiving space extending the length of the arrays and which clampingly receives an elongated straight portion of a serpentine electric defroster heater in good heat conductive contact with each fin of the immediately adjacent pair of finned tube arrays. Each fin of the stacked assembly has at least two corners in engagement with the heater. The stacked assembly is disposed transversely in a duct having an air inlet and air outlet.