The answer to 'duct cleaning freezing up' is that a frozen air duct is typically caused by a blockage or restriction in airflow. This can happen when the duct cleaning process is not done properly, leading to debris buildup that restricts airflow and causes the ductwork to freeze. Symptoms may include reduced airflow, uneven heating/cooling, and icy duct surfaces.
In most cases, this issue can be resolved by thoroughly cleaning the ductwork and ensuring all blockages are removed. However, if the problem persists, it may indicate a more serious issue such as a refrigerant leak or HVAC system malfunction that requires professional diagnosis and repair.