If you remove the filter it will operate as you expect, exhausting air from the chamber. What I suspect is happening is that the filter creates enough restriction that instead of drawing only air through the filter, there is air that is dawn in between the somewhat large clearance between the fan blades and the outer ring of the fan. This is why you “feel” air being drawn in when it is really just being drawn in out outside edges of the fan and exhausted more towards the center.