Abstract: A film valve assembly for a heating, ventilation, and air conditioning system includes first and second rollers disposed rotatably on a frame, a film valve, and a driving mechanism. The driving mechanism includes a driving member, and a speed reduction gear unit disposed between the driving member and the first roller. The driving member is operable so as to activate the speed reduction gear unit, thereby rotating the first roller on the frame in a selected one of opposite first and second directions. The second roller is biased to rotate in the first direction. The film valve has two ends coupled respectively to the first and second rollers.