Went to get something to eat this evening and the whole way there everything was fine. Got back in after about an hour and cranked the heat up and noticed an unusual vibration. The noise and vibration goes away when the heat is turned off and comes back when turned on. Is this just my blower unit going out or is it possible to have sucked something up that would cause some noise and vibration? If I remember correctly it was fine at first when it was on recirculation, then I flipped it to fresh and thats when it started making noise and vibrating. Now it makes noise on either setting. Any ideas? thanks.