Causes of Ice Buildup on Air Conditioners

01/31/2024 | Comfort Zone of North Florida, Inc | Air Conditioning

When airflow to your air conditioner gets blocked, ice builds up on the exterior unit and the condenser coils. Changing the air filter for the unit each month offers the simplest prevention for this, but read this blog to learn how to repair blocked airflow causing an iced over unit.

How Evaporator Coils Function

Warm air blows over the evaporator coil on the interior portion of your air conditioner unit, but refrigerant running through the system cools the coil. The unit needs a warm air flow to keep the refrigerant from freezing the coil.

The air filter in the interior of your home that works with your air conditioning unit ensures it remains free of debris and blockage. These air filters only last about one month. Changing the air filter helps the unit run more efficiently and keeps the airflow unblocked.

What Causes the Coil and Outside Unit to Freeze?

A dirty filter, filled with debris, blocks the warm air from entering the vent system and reaching the evaporator coil. This blockage allows the temperature of the coil to drop below freezing, causing ice to form on the coil and on the exterior air conditioning unit.

Things to Check When the AC Seems to Stop Working

If you notice the interior air seems less cool, or the air conditioner doesn’t seem to blow air appropriately, walk outside and check the exterior unit. If you note ice on the unit, then your evaporator coil froze. In most cases, you can fix this yourself.

How to Fix a Frozen Coil and Exterior Unit

The entire process requires about six hours to repair. If this occurs during particularly hot weather, set up a window unit to keep the inside of your home bearable while you make repairs.

Turn off the central heat and air unit completely. Leave it off until the coil and the outside unit thaw out completely.
Inside your home, check the air conditioner filter for disrepair and cleanliness.
Replace a dirty, torn or bent filter with a new, clean one of the appropriate size.
Turn the unit on again after thawing it completely.

Avoid trying to hurry things along by scraping or chipping off the ice. You could damage the air conditioner or coil, and it will only remove the exterior ice you can see. It won’t induce the interior of the unit to thaw more quickly.

What If the Air Conditioner Still Does Not Work?

Examine the evaporator coil for clogs. Hair and dirt commonly plug up their ability to function properly. Cleaning the coil may restore proper function to your AC.

If the unit continues to malfunction, it could be any of the following four issues: