recently we have a bad smell coming from our heating vents in the living room. we have central heat/air. last year an older cat was spraying the house indoors, we replaced the carpets with tile and thought that the smell was gone, until now. the smell is so bad that we pulled up the tile to replace and it was fine, the smell is coming from the vents in the floor. HELP!!!!

Cat pee in the duct ? Spray it down with the blower off. Use a good cleaner or pinesol.