To surely close a passage in which a refrigerant circulates through a communication hole opened in a connecting section of a cooling means, and to surely and easily perform the attachment and detachment of a dust preventing cap to the connecting section.

An evaporator 14 which is adopted for the air-conditioner 10 for a vehicle is provided with connecting blocks 30 at ends of a pair of pipe arrangements 28a and 28b in which the refrigerants circulate, and first and second holes 36 and 38 which communicate with the pair of the pipe arrangements 28a and 28b are formed. Then, on the connecting block 30, the dust preventing cap 52 which prevents dust, dirt or the like from entering the inside of the evaporator 14 through the first and second hole sections 36 and 38 is fitted. The dust preventing cap 52 comprises a body 54 equipped with first and second fitting sections 56 and 58 which close the first and second holes 36 and 38, and a hook 60 which is formed in a manner to protrude from the body 54, and pulled when the body 54 is detached from the connecting block 30. The hook 60 is formed to be freely turnable to the body 54.