Well one of the large intake air vents in hallway floor of my house smelled of litterbox...the litterbox is in the bathroom and cleaned regularly. It smelled like old air with a tint of cat urine or litterbox smell every time the CA kicks on. We have cleaned the vents out before we started it up this morning. Now, how to get rid of the smell and smelling good thru the summer months?? I thought about used dryer lints in the intake vents and out take vents (where the cool air comes out). would this work????? Also, my daughter and I have issues with allergies, would one get some kind of filters for the vents? Any ideas and suggestions are welcome to make my OLD house smelling good!