Our air duct sealing process is done from the inside of your ductwork, so we are able to seal all the cracks and leaks without ripping into your home. Every home has some amount of air duct leakage, and here is how you can tell if yours is bad: Uneven heating/cooling in the home (hot and cold spots), temperature differences between levels, furnace or AC that runs all day long, excessive dust/allergens in the home, high heating/cooling bills.