Why Is My Central AC System Frozen?

You may have noticed that your home’s central AC system is running continuously but the temperature is rising. You may feel a decrease in airflow coming from your central AC system’s registers yet the air feels cool. These are signs that your outdoor unit may be icing up.

Figuring out what is causing your system to freeze up can be frustrating but it is a common problem.

What Can Cause Your Central AC System to Freeze Up?

The evaporator coil is located in the outdoor unit of your central AC system. It is the evaporator coil that is freezing up. There are 3 main reasons that can cause the evaporator coil to ice up.

  • Airflow restriction: Anything that obstructs or prevents air from flowing across the evaporator coil can cause it to freeze up. This could be a buildup of dirt or leaves, dirty filters or a damaged blower motor.
  • Insufficient refrigerant: Refrigerant leaks or a low refrigerant level can over chill the evaporator coil and cause moisture in the air to freeze and build up.
  • Air Temperature: A faulty system thermostat or one that is set too low can cause your central AC system to run constantly and eventually cause an ice buildup. Most outdoor units do not function well in colder temperatures (below 60 degrees F). Low night time outdoor temperatures can cause freezing up.

What Should You Do When Your AC System Freezes Up?

  • Turn your Central AC system completely off and allow it to defrost completely. Don’t use a heater to defrost your outdoor unit.
  • Change dirty filters and clear away any obstructions that could be restricting airflow on your outdoor unit.
  • Open up all registers completely and remove anything blocking airflow such as furniture or draperies.
  • If you still experience freezing up on your system, contact your local AC repair company to inspect and service your central AC system. The technician will diagnose and repair your system and prevent this problem from recurring.