AC Parts Freezing Up? Your High-Efficiency Air Filter May Be The Culprit

1 September 2015
 Categories: Business, Articles


Even the end of summer can be atrociously hot and sticky. If your AC stops putting out cold air and freezes up, your situation becomes critical. Before you panic, take a second and look at your high-efficiency air filter. Your high-efficiency air filter may be the culprit behind your poorly performing AC. Here are things to know about high-efficiency air filters, why your air conditioning system's parts freeze up and how you can protect your system in the future.

Aren't High-Efficiency Air Filters Good for Your Home?

High-efficiency air filters use a special system called HEPA, or High Efficiency Particulate Air, to protect your indoor environment from dust mites, mold and other airborne microorganisms that cause respiratory problems in humans and pets. HEPA air filters can block the airflow through your system if they clean your home too well. As a result, ice forms on your indoor air handler and outdoor AC unit. 

Here's why.

HEPA air filters remove up to 99 percent of airborne contaminants from your home. The contaminants stick to the surfaces of the air filters, which keeps them from passing through your cooling system. Because HEPA filters work so efficiently, the contaminants they attract build up on their surfaces until they block the air circulation through your indoor unit's evaporator coil. 

The evaporator coil is the large, triangular apparatus found inside the indoor air handler. The coil collects heated air and redistributes it into the home as cold air. The coil also relies on an undisrupted airflow to perform these actions throughout the day and night.

If the evaporator coil doesn't receive enough heated air to keep the water inside it in liquid form, the water turns into ice and spreads to the outdoor unit. This is when you run into major problems.

Why Did Ice Form on the Outdoor Unit's Copper Pipeline?

The evaporator coil sends heated air to the outdoor unit through a thin, copper pipeline. The pipeline is designed to circulate cold air back to the indoor unit as well. If the line doesn't receive heated air, it forms thick, hard ice on its surfaces and freezes.

The outdoor unit's motor works double time to push cool air back into the home. After awhile, the motor makes loud grinding noises and breaks down. In this case, you need to contact an HVAC repair contractor to replace it.

You can prevent the issue above by doing something now.

How Do You Thaw Out Your Air Conditioning System?

Thawing out the evaporator coil is one thing you can do to protect your cooling system from disrepair. You'll need a few things to get the job done, including a:

  • Large bucket of warm water and soft cloth
  • Blanket or sheet to protect your flooring from water
  • Squirt bottle with an adjustable nozzle filled with white vinegar and hot water

First, look over your cooling system's owner's manual and find instructions on how to remove the paneling over the air handler's evaporator coil. Once you do, follow the instructions below:

  • Cover the flooring beneath the air handler with the blanket or sheet
  • Turn off the entire cooling system at the breaker box, then wait at least 2 hours to give the ice on the evaporator coil time to soften up or thaw
  • Use the spray bottle to soak each side of the evaporator 
  • Give the vinegar solution 30 minutes to penetrate the debris on the evaporator coil's surfaces — don't touch the sharp metal pieces or fins on the coil, as they can break or bend very easily
  • Use the warm water from the bucket to wipe down the inside and outside of the air handler, then wipe down the copper pipeline attached to it

After waiting 20 additional minutes for the housing to dry inside and out, replace the coil, secure the paneling and return power to the cooling system. The ice coating the copper pipeline should melt inside and outside the home but still feel cold to the touch. 

What Type of Air Filter Should You Use?

After completing the steps mentioned above, replace your high-efficiency air filter with a MERV rated air filter. This type of air filter removes contaminants between .3 to 10 microns in size, which includes dust mites and pet dander.

Most MERV rated air filters feature larger pores or openings on their surfaces, which gives hot and cold air enough room to circulate through them properly. Your system's evaporator coil and copper pipeline won't freeze up because of this. 

Also, change the filter every three months or sooner if it looks visibly soiled or dirty. You want to keep the airflow in your home clean, as well as unrestricted.

If you need additional help with your air filter or cooling system, contact your HVAC repair contractor, like one from Air Conditioning & Heating Inc, today.