The answer to 'why is my humidifier freezing up' is that a humidifier can freeze up due to low water temperature, low humidity settings, or a malfunction. This can happen when the humidifier is working too hard to add moisture to the dry air, causing the water inside to freeze and block the airflow.
Some common symptoms of a frozen humidifier include reduced or no humidity output, visible ice buildup, and the unit shutting off unexpectedly. To fix a frozen humidifier, you can try increasing the humidity setting, cleaning the unit, or checking for any blockages. If the issue persists, it's best to call in a professional HVAC technician to diagnose and repair the problem.