I have just bought a 1 yr old home and have been wrestling with a weird problem. Basically, I hear a high frequency noise (with modulation) coming from the air return vent in my master bedroom. The noise somes only if I close the door, and it dissapears when I open it or open the window. This tells me that there air is trying to get out and it
does not get out fast enough through the return vent thus causing the noise. I have this problem with a room upstairs that has no return vent.
Thanks for any insight.
I called in the heating/ac contractor for the house and he said that's normal and nothing he can do about it. I find it hard to believe because there are other houses in the neigborhood with the same floorplan and I can't imagine that we are all having the same problem.