The answer to 'HVAC system freezing up' is that a frozen HVAC system is a common issue that can be caused by several factors, including low refrigerant levels, a dirty air filter, or a problem with the blower fan. Symptoms include ice buildup on the coils, reduced airflow, and poor cooling performance.
Some common solutions include checking and replacing the air filter, cleaning the coils, and ensuring the refrigerant level is correct. However, if the issue persists or you're unsure of the cause, it's best to call a professional HVAC technician to diagnose and repair the problem.