The answer to 'why is my central air freezing up' is that a frozen evaporator coil is the most common cause. This happens when there is restricted airflow over the coil, causing it to get too cold and freeze up. Some common symptoms include reduced cooling, ice buildup on the coil, and the compressor cycling on and off frequently.
There are a few potential reasons for a frozen coil, including a dirty air filter, a refrigerant leak, or a problem with the blower motor. It's important to address the underlying issue to prevent further damage and ensure your system is running efficiently.