The answer to 'air duct sealing freezing up' is that this issue is typically caused by a problem with the HVAC system, such as low refrigerant levels, a blocked air filter, or a malfunctioning blower fan. When the air ducts are sealed, it can restrict airflow and cause the coils to freeze up, leading to reduced heating or cooling efficiency and potential damage to the system.
To troubleshoot and resolve this problem, you should first check the air filter and replace it if it's dirty. Next, inspect the blower fan to ensure it's running properly. If the issue persists, it's best to call a professional HVAC technician to diagnose and repair the underlying problem, as they have the expertise and equipment to properly service the system.