The answer to 'why is my thermostat freezing up' is that a frozen thermostat is often caused by a problem with the HVAC system, such as a refrigerant leak or a blocked air filter. This can cause the thermostat to become too cold and freeze up, preventing it from accurately reading the temperature and properly controlling the heating or cooling system.
Some common symptoms of a frozen thermostat include the system not turning on, the thermostat display showing an abnormally low temperature, or the thermostat feeling cold to the touch. If you notice these issues, it's best to call an HVAC professional to diagnose and repair the problem, as attempting to fix a frozen thermostat yourself could potentially cause further damage to the system.