An air duct system may employ an HVAC case having an exit air duct and a return air duct, a windshield with an interior surface, an approximately vertical duct, and a horizontal duct. Ducts mount to the windshield and each define an interior passageway with the interior surface of the windshield and a second, return air, passageway. The interior passageway may receive air from the exit air duct and the second passageway may return air to the return air duct. End chambers of each duct reverse air direction 180 degrees. Air of each interior passageway may warm an adjacent area of the windshield that forms part of each interior passageway and a windshield wiper. The first air duct interior passageway may warm a windshield area coincident with a maximum non-park wiper position and the second air duct interior passageway may warm a windshield area coincident with a wiper park position.