Home Suddenly Feels Warm? Your Air Conditioner’s Evaporator Coil Might Be Frozen

If your home suddenly feels warm, check the evaporator coil for ice. During the summer, your evaporator coil works overtime to remove heat from the home and replace it with cool, comfortable air. But sometimes, the evaporator coil becomes clogged with debris and stops absorbing heat and freezes. A frozen evaporator coil has the potential to create a number of problems with your cooling system and home, including mold growth, a infestation of dangerous flies and a damaged compressor. You can unfreeze the evaporator coil and cool down your home with the information and tips below.

Why and How Does the Evaporator Coil Freeze Up?

Much of the warm air absorbed by the evaporator coil contains moisture. To get rid of the moisture, the evaporator coil condenses or changes it to water, which empties into the condensate pan positioned at the bottom of the coil. When the pan becomes full, the water flows into a drainage line that empties it outside the home or into a sump pump. But if the coil becomes blocked with debris because of a dirty air filter, mold or another hazard, it can't get rid of the heat or moisture it receives.

Instead, the coil forms a sheet of ice over it that may slowly melt and drip into the condensate pan, which overflows into the drainage line and clogs it up. You might notice water on the flooring beneath your air handler as the condensate pan overflows and the ice on the evaporator coil melts. The clogged drainage line may develop mold and other types of fungi and organic matter that attract annoying and dangerous pests called phorid flies. The flies feed off the organic matter inside the drainage line and may carry diseases that can cause illnesses in humans if the pests contaminate your food or other items with germs.

Allowing the evaporator coil to thaw and cleaning out the drainage line and condensate pan may be the best ways to prevent the problems above.

How Do You Unfreeze the Evaporator Coil and Clean the Condensate Pan and Drainage Line?

To get started, turn off the air conditioning system at the thermostat and circuit breaker, then spread a plastic tarp beneath the air handler to protect the flooring. Allow the evaporator coil time to thaw. The thawing time may vary, so it's a good idea that you remove the paneling from over the coil and check back regularly to see if it's free of ice.

Next, you'll need to get a few things for the cleaning, including a water pitcher filled with 3 cups of white vinegar and 1 cup of hot water and two cleaning rags. The vinegar will help clean out the clogged drainage line by destroying the mold and other organic matter.

After the evaporator coil thaws out, examine it to see if appears soiled with dirt. If so, use a spray bottle filled with 2 cups of hot water and 2 cups of vinegar to clean it. If the coil appears free of dirt, follow the steps below to clean the drainage line and condensate pan:

  1. Remove the condensate pan from beneath the coil, then empty the water outside the home or down the toilet.
  2. Use the rags to wipe out the condensate pan.
  3. Detach the white PVC drainage line from the air handler. The line connects directly to the condensate pan to help you find it easier.
  4. Pour the vinegar and water solution from the water pitcher down the drainage line. Look inside the line to see if it's clear. If not, repeat step four until the line appears visibly clear.
  5. Replace the condensate pan, then reconnect the drainage line to it.
  6. Replace the paneling over the evaporator coil, then remove the tarp. 

Return power to the AC system, then wait an hour or two to see if it cools the home. If the home feels cool and comfortable, you solved the issue.

If the home remains warm after the time mentioned above lapses, contact an air conditioner contractor, such as those at Controlled Comfort, for help.