Why Does My AC Freeze Up On Me?


When the refrigerant escapes due to a fault in the containment system, there is a drop in pressure which makes the indoor part of your AC get cold – well below freezing. This leads you to ask, WHY DOES MY AC FREEZE?

You have a loss of refrigerant either in the indoor or outdoor systems, or the containment system between them. The leak is usually slow.

One reason this could have happened is due to an installation fault. The installation contractor could have used inferior materials and practices like soft soldering the joints together, which always seem to eventually leak. Brazing the lines is the proper method in most applications.

Damage can occur to the refrigerant containment system, making it freeze everything up. Even we, once in a while, have a frozen AC and find that someone was doing some remodeling and drilled a screw into it. This type of damage tends to leak out refrigerant a bit faster!

The next likely suspect happens to be on the inside unit in the heat absorption coil. Damage here can happen due to age, design fault (the manufacture had an issue), or the system operating in an acidic environment of which I have only seen in a commercial application.

Once there is a fracture fault in the heat absorption system, that half of your AC system needs to be replaced as it will only get worse and lead to costly AC service and repairs.


You see, a certain amount of air needs to pass through the indoor half of the AC to keep it from turning into an ice cube. The only thing that keeps it from freezing is the warmer indoor air passing through the air handler to be cooled and de-humidified and then redistributed through the home.

There can be anything from a mechanical failure of the indoor air movement system or a bad thermostat which fails to send power to the equipment that moves the air but yet tells your AC to be on. These two things will have you making enough ice for your Labor Day holiday!

More often, we see that the inadequate air delivery system is due to the home being built when the building code standards were lower. In the last 25 years or so, give or take, many builders try to save money on the HVAC portion of the project. This is often because they know very little about it, don’t want to give proper room for the proper size delivery system, and choose to put money in other parts of the house. The wrong size system can lead to more repairs because it runs at higher than designed temperatures. The fix for the issue will vary in complexity but is often on the simple side.

This last cause of inadequate airflow, neglect and a lack of maintenance, is as common as the one above. Yes, changing your filter monthly is included because if neglected it restricts the air movement system and the heat absorption system. The problems can be avoided with regular maintenance and regularly changing your HVAC filters.

1/8th of an inch of dirt on the indoor air movement wheel can reduce air flow up to 30% according to a Texas A&M Study. A build up of 1/20th of an inch of dirt on the heat absorption system can result in a 21% DECREASE in efficiency according to the EPA.

I don’t know if you agree, but that much grime will also add to bad indoor air quality (Yuck HaChoo!). The good news is this is the easiest of all the major problems to prevent. Have annual maintenance that includes the tech inspecting to see if anything is wrong with your AC before you really need it in the hot Chicago dog days of summer. Another benefit is having your AC running in tip top shape at the best efficiency possible.

Always at your service,


Author: Tom Hack
Company: A Custom Heating and Air Conditioning

About A Custom Heating and Air Conditioning:

Celebrating our 24th year in business. We are a residential Heating, Air Conditioning, Water purification, Air Purification, and Air Balancing company on Chicago’s North West Side. We service, maintain and install all residential products. Whether you are suffering from uneven temperatures from floor to floor or suffering from allergy’s that make you feel un comfortable. WE have a solution for you.
Email: acustomhvac@gmail.com
Phone: 773-319-0922

Categories: Air Conditioning.