So as you may know if you set the heater flap to on you get some extra engine noise in the cabin.:bang: Because of hot Greek summer every season i am disconnecting the heater flex duct to let extra hot air extract out and also to avoid any hot leaks in the cabin. This year i didn't put back the flex rubber duct and wait for the cold. Well after a while hot air still comes to the cabin not as hot as before but more than enough to keep you warm. More important noise is reduced by 90%.