The most common cause for a frozen AC is a low refrigerant level. This may sound counterintuitive, but when levels are too low, the pressure within the system drops, and the remaining refrigerant can’t absorb as much heat. Moisture from the air outside the evaporator coil freezes on the outside of the coil, then ice builds up, further compounding the issue until your system seizes up entirely. Other potential culprits include blocked airflow in your ducts, vents, or outdoor units. That’s why regularly replacing your air filter is one of our top air conditioner maintenance tips!