Cooling system problems are something all homeowners in the Northern Kentucky and Greater Cincinnati areas want to avoid when it’s hot outside. If you have an AC unit that is freezing up in the summer, this issue can definitely put a damper on your family’s comfort. Rusk Heating and Cooling explains why your air conditioner may freeze up this season and what to do to stop it from happening again.

What Causes an AC Unit to Freeze Up in Summer?

A frozen HVAC system is usually traced to a few critical causes:

1. Poor Airflow

To cool your home’s air, the evaporator coil within the indoor unit absorbs heat from within the air. The refrigerant inside the coil warms as it extracts heat from the air, keeping the evaporator coil warm, too. If the system isn’t maintaining proper airflow throughout, not enough warm air will pass over the evaporator coil and the refrigerant won’t gain enough heat to keep the coil temperature up. When there is low airflow through the system, your air conditioner can freeze up, as frost and ice will form on the evaporator coil.

2. Low Refrigerant

In addition to proper airflow, your cooling system needs a precise volume and charge of refrigerant to prevent an AC unit from freezing up in summer. Leaks in refrigerant lines and other system components cause the cooling system to lose refrigerant, robbing your air conditioner of the coolant it needs for heat transfer. Without proper refrigerant volume, there is not enough coolant to absorb heat and warm the evaporator coil, so the coil freezes.

3. Dirty Evaporator Coil

In order to remove heat from the home’s air, energy has to pass from the air to the refrigerant through the evaporator coil. Debris from the air can collect on the evaporator coil as air continuously circulates through the unit, covering the coil’s surface area. Mold growth can also stick to the surface of the coil. When too much of the coil’s area is covered by debris, grime, and/or mold, heat cannot pass through the coil and refrigerant will not warm, resulting in a frozen central air conditioner.

Prevent a Frozen AC Unit

An AC unit that freezes up in summer will stop your home from receiving the cooling it needs to stay comfortable. If you see ice or frost forming on your evaporator coils, it’s important to shut down the system and allow the coils to thaw, as continuing to run your cooling unit while it’s frozen can cause damage to the system. You can turn on the blower fan at the thermostat to keep warm air circulating over the coils, helping them to thaw quicker. Repairs may be needed to solve the underlying cause of your frozen air conditioner.

Many times, a frozen air conditioner is caused by an airflow issue, commonly the result of dirty air filters. Airflow issues are easily solved with some troubleshooting measures in most cases. These tips will help you prevent your evaporator coils from forming ice and stopping the cooling process.

  • Remove the existing dirty air filter and replace it with a fresh, new filter.
  • Make sure all vents and air returns throughout the home are open and unblocked by furniture, carpets, and other materials.
  • Clear away debris that has gathered upon the walls of the outdoor unit, which restricts heat transfer and blocks airflow needed to facilitate the cooling process.

If your AC is freezing up in the summer because its evaporator coils are dirty, you can carefully clean debris to help the coils function effectively.

  • Turn off power to the air conditioning system.
  • Access the evaporator coil by removing the panel.
  • Use a soft cleaning brush or cloth to wipe down the coils and remove debris. 
  • Mix a solution of basic detergent and warm water in a spray bottle and apply it to the coils. Let the solution sit on the coils for several minutes to loosen deposits before wiping them away.
  • Once clean, replace the panel and restore power to the air conditioner.

Air Conditioning Repair for Frozen AC Units

If troubleshooting doesn’t fix your frozen air conditioner, the cause may be a refrigerant leak or other mechanical failure that requires professional repair. Call Rusk Heating and Cooling to schedule air conditioning repair service that will stop your coils from freezing this season.