Hi everyone. I have an annoying whistle from my interior fan when the blower / AC is running, getting louder on the higher speeds. It stops when I turn the blower off, so I'm pretty sure it's the fan motor. Has anyone here changed one (2010 E89 23i)? If so, is it a fairly straightforward job? I need to drop the underdash panels soon, so it feels like a good time to do it. Any advice?