Surface treatment agent for aluminum heat exchangers and surface treatment method

A surface treatment agent for an aluminum heat exchanger, comprising:

• a zirconium element;
• at least one vanadium element selected from a group consisting of vanadyl sulfate, vanadyl nitrate, and vanadyl phosphate;
• an acrylic polymer obtainable by polymerizing a monomer including at least one kind selected from a group consisting of acrylic acid, methacrylic acid, and derivatives thereof;
• an aluminum element;
• and
• a fluorine element;
• wherein
• a concentration of the zirconium element is 100 to 100,000 mass ppm in terms of zirconium;
• a concentration of the vanadium element in terms of vanadium is 50 to 100,000 mass ppm;
• a concentration of the polymer is 100 to 100,000 mass ppm;
• a concentration of the aluminum element in terms of aluminum is 5 to 10,000 mass ppm;a concentration of the fluorine element is 125 to 125,000 mass ppm;
• and
• a pH is 0.5 to 3.