The answer to 'air duct sealing blowing cold air' is that air duct leaks are a common problem that can cause cold air to blow from your HVAC system. This is often due to gaps or cracks in the ductwork that allow conditioned air to escape instead of circulating through your home.
Some common causes of this issue include poor initial duct installation, damage over time, or inadequate sealing. Symptoms may include uneven heating/cooling, higher energy bills, and reduced airflow from vents. The solution is to properly seal and insulate the ductwork, which can be a DIY project for some homeowners but may require a professional HVAC technician for more extensive repairs.