Why does my AC keep freezing?

Why does my AC keep freezing repeatedly indicates ongoing underlying problem not fixed by just thawing ice, causing evaporator coil temperature to repeatedly drop below 32F. Common reasons AC keeps freezing include persistent low airflow due to dirty air filter that you haven't replaced, dirty evaporator coil that needs cleaning, blower motor running slow or failing, or many supply vents closed blocking air, all reducing heat over coil. Low refrigerant charge due to slow leak causes low pressure and low temperature, leading to repeated freezing, if leak not repaired charge drops again. Faulty thermostatic expansion valve TXV stuck closed or clogged filter drier restricts refrigerant flow, starving evaporator and causing freezing. Running AC when outdoor temperature is below 60F or at night when too cool can cause freezing. Thermostat set too low below 68F causing continuous operation. Drain blockage causing water to refreeze. If AC keeps freezing after changing filter and thawing, you need professional diagnosis to check refrigerant level, leak detection, TXV operation, blower, and ductwork, as continued freezing can damage compressor and increase bills, so address root cause promptly.