Thats whats up! How big is your filter? To help until you get a new one, you might want to try taking some plastic wrap, the shit you find at the grocery store and wrap the top half closest to the fan, so the air is forced to be drawn through the charcoal at the bottom. Over time, the charcoal settles and air, like all of us, wants to take the path of least resistance, which is most likely closest to the fan. The bottom half of your filter might barely be used since the air isnt drawn into the filter equally from all points. I'm not saying you'll get another year out of the filter, but it might buy you a little more time if needed