To manufacture in a short time and to reduce its cost in a heat exchanger for an evaporator of an air conditioner having a refrigerant circuit constituted by adopting a capillary tube.
In the case of connecting a capillary tube 106 to one end of a refrigerant circuit made by connecting a U-bend tube 173 to ends of a plurality of hair pin tubes 172 by brazing, an end of the tube 106 is enlarged or contracted to match a foremost end enlarged or contracted at the end of the tube 106 to a size of the tubes 172 for constituting an engaging part of one end of the circuit to a size connectible by brazing. Then, the foremost end of the tube 106 is directly inserted into the flared enlarged tube of the tube 172, brazed to constitute the refrigerant circuit. Thus, the brazing work is reduced, a manufacturing time is shortened, its cost is decreased, and reliability, economy or the like is enhanced.