Not all signs of furnace problems and failure are immediately apparent. Some sounds, smells, and operating behaviors can point to issues that are growing serious even if your furnace still seems to be running and heating normally. If you notice any of these signs, your furnace likely needs repairs before it experiences or causes any damage.
Strange Odors from Ducts
Some smells from your ducts are very normal. If you haven't run your furnace in a long while, a slight burning smell is normal due to dust and other debris that may have collected.