Aluminum alloy heat exchanger resistive to tobacco odor impregnation

An aluminum alloy heat exchanger resistive to tobacco odor impregnation, comprising a base body of an aluminum alloy heat exchanger and an organic hydrophilic coating layer formed on at least a portion of the surface of the base body, wherein the organic hydrophilic coating layer comprises the following components (A), (B) and (C):

• (A) at least one chitosan compound selected from the group consisting of chitosan and derivatives thereof;
• (B) at least one carboxylic compound having at least two carboxyl groups per molecule thereof;
• and
• (C) at least one hydrophilic polymeric substance different from the above-mentioned compounds for the components (A) and (B),
• the components (A) and (B) in the organic hydrophilic coating layer being present in a total solid content of 20% by mass or more, and
• the component (C) in the organic hydrophilic coating layer being present in a solid content of 0.1 to 10% by mass.