My newly installed Carrier furnace makes a thumping sound immediately after it shuts off. The sound only occurs if the furnace blower has been operating. I hear the sound near the unit's vent pipes, and it is loud enough to hear throughout my condo. Any ideas?
I moved into a new home two months ago and the home inspection noted no problem with the furnace. Recently I noticed that the furnace has some black stuff around the tubing that is coming out of the side of the unit and a smell in the house. Is this normal or is it something I should be concerned about?