I have just bought a split level ranch that has two debrooms in the upper level. Any day I'm home in the afternoon I can smell a reaaly strong odor from the two bedrooms. I have literally put my nose to the vents and don't think it's coming from there. I tried to isolate the smell and right now I'm down to the floor or the walls. I haven't really ruled out the heating/ac system yet though.

The strange thing is that the smell is only there for a couple of hours each day. It's gone at night. The smell is not foul but is really strong. I cannot say what it is like but is acidy like. And it seems to happen when the sun shines in the bedroom windows. I know this might sound daft but that's the only pattern I can see right now.

Any help will be appreciated.