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What to Do When Your AC Unit Freezes Up

Imagine your air conditioning system working fine day after day during the hot Central Indiana summer, seeming almost invincible to whatever Mother Nature throws its way. Then one day – out of nowhere – it stops working.

As the temperature in your home begins to rise, you look for a quick fix to restore normalcy back into your life. You shut off the power to the air conditioner at the thermostat and remove the cover of the indoor unit to try to see if there is any obvious reason for the problem. Then you see something you’re not expecting to see in the middle of summer – a frozen air conditioning evaporator coil.

To help you understand how to fix a frozen air conditioner coil, we’ll discuss the basics of how your air conditioner works and what could cause a frozen AC coil. For all of your air conditioner repair needs, contact the friendly, NATE-certified technicians at Star Heating & Cooling. We’re Fishers, IN, and all of Central Indiana’s number-one and most trusted HVAC company.

How Does an Air Conditioner Cool Your Home?

When the air handler blows warm air over the coil, the refrigerant inside the coils absorbs the heat and cools off the air. This cooling process also dehumidifies the air, causing condensation. The moisture from condensation usually drips off safely into the condensate drain.

But when the airflow of your air conditioner is restricted, it can cause this condensation to freeze right on the coil. As long as this continues, more layers of ice start to build up. This can result in a thick layer of ice that completely encloses the evaporator coil and causes the system to shut down.

What Causes a Frozen Evaporator Coil?

There are several reasons an AC freezes up. Some of the top ones include:

  • An extremely dirty air filter. A clogged air filter can result in total blockage of airflow. In cases airflow is restricted or blocked, the evaporator coil can’t properly move heat, causing the system to freeze over.
  • A dirty evaporator coil – often the result of no filter or an air filter that hasn’t been changed in a long time – can also cause restricted airflow.
  • An outdoor unit that is completely covered in cottonwood or other debris.
  • Low refrigerant levels caused by a leak somewhere in the system.
  • Vents blocked by furniture, heavy curtains or other items that seriously restrict airflow and prevent the system from operating properly.

What to Do If your AC Unit Has a Frozen Evaporator Coil

While you wait for an air conditioning technician to arrive, you can simply leave the unit shut down. However, you can help speed the thawing process by turning the fan on low. You can also go around your house to check to see that there is anything blocking any of the return air registers that could have contributed to the problem in the first place. If you feel confident about repairing the issue yourself, check out this article from

If a frozen AC unit evaporator coil is caused by low levels of refrigerant in the system, some air conditioning companies will offer the temporary fix of “topping it off” to bring the level back up. The technicians from Star Heating & Cooling will never simply top off the level without finding the leak in the system that caused the problem in the first place.

Contact Star for All of Your AC Repair Needs

If you live in the Hamilton and Marion counties and your AC unit has a frozen evaporator coil, please contact Star Heating & Cooling at 317-753-0279. We are dedicated to helping you keep your home comfortable. We offer on-time and dependable service, including free emergency service 24/7. Our technicians will have your air conditioning back up and running in no time.