My heater/AC makes a whistling noise at high fan speeds, and even at lower speeds (3-4) when driving 60+mph unless I switch to recirculate. Dealer re-positioned the cabin filter which seemed to help for awhile, but it has recurred. New cabin filter did not help. Dealer checked 3 other iPaces and says they all do this. Has anyone else experienced this and/or found a solution? (I'm considering removing the cabin filter...)