Why is My AC Freezing Up?

AC Freeze up

Air conditioner with frozen ice and icicles. Cooling, cold temperature concept image. Aged wall background.

AC freezing up? How can something that works all day during the hottest days of the year be prone to freezing?

Despite the ironic happening of an AC freeze in the summertime, air conditioners freezing up is something that happens a lot. Not many homeowners are equipped with the knowledge and understanding of air conditioners to prevent this problem on their own.

The heat and humidity in the south during most of the year can put a strain on your AC, causing unexpected outages and even mold and mildew growth. Don’t damage your air conditioner and live with malfunctions any longer.

Below are some possible reasons why your AC is freezing up, and what you can do to address the issue. The short answer is that whenever there is blocked airflow through any of the air conditioner’s components, a portion of the AC will freeze. There are several things that could cause blocked airflow: dirty air filters, clogged condensate line, dirty coils, refrigerant leak, a faulty fan, among others.

Understanding the Joule-Thomson Effect

Before we delve into the causes of an AC freezing up, let’s talk a little bit about how your AC works. First, we must understand that temperature is how much energy a molecule has. When the air feels hot, it’s because the molecules in the air have a lot of energy and are moving around rapidly.

So, what the Joule-Thomson Effect demonstrates in thermodynamics is when the air in our ACs isn’t compressed, its temperature will decrease as it expands and the molecules slow. When it is compressed, the molecules get excited and heat up. The point of an air conditioner is to expand the refrigerant inside the evaporator coil so that it cools down, so when it leaves the air conditioner, it cools the air inside your home and effectively removes the hot air from inside the house.

The Supply Registers

How can you tell if you might be facing a freezing problem?

A sure sign is to check the supply registers. Is it warm? If so, that’s a good indicator of frozen evaporator coils. Open the panel and check for ice. Keep in mind, a lack of ice doesn’t necessarily mean that you’re not having a freezing problem.

Your AC Needs Proper Airflow

There are many reasons why your AC unit may be freezing up. Air conditioners need proper airflow to keep the cold coil warm.

Warm air from the home is needed for the coil to stay cold and keep the temperature above freezing. Without it, coils freeze before the condensed water can be drained away from the unit.

Low Refrigerant or Fan Issues

A freeze-up can also be caused by low refrigerant and improper fan operation. Low refrigerant levels make the coils too cold, and a faulty fan prevents air from moving.

Faulty Thermostats

Faulty thermostats and drainage problems are often causes of a freeze up. In the cooling process, an AC unit condenses water vapor into a liquid that drains outside. The AC still runs, but doesn’t properly cool the home and uses a lot more electricity.

Blocked Drain Pipe

It’s also a good idea to check the drainpipe for any blockages, such as debris and twigs. Keep in mind that running an air conditioner with frozen coils can lead to extensive damage to the compressor.

Get a Humidistat

A humidistat is a device that regulates the humidity inside your home. In a muggy climate like we have in Georgia, we recommend installing a humidistat because if the humidity level inside your household goes above 60%, you could face the following issues:

  • Windows and door frames can expand, causing air leaks
  • Mold spores start growing in your home
  • Book pages start turning yellow
  • Bacteria that cause illnesses will have a perfect environment to grow
  • Allergy and asthma sufferers may experience respiratory issues
  • Your AC works overtime because it has to work longer to absorb all the moisture in the air
  • This, in turn, increases your energy bills and the amount of condensation in the coils
  • Too much condensation that can’t drain results in a frozen air conditioner.

Whatever The Culprit, Call In a Professional

Other than that, since there could be so many culprits, it’s crucial to have preventive AC maintenance on a regular basis. This can extend the lifespan of your air conditioner (saving you money in the long run) and prevent health hazards such as refrigerant poisoning due to a Freon leak.

If you’re short on time or on patience, you can speed up the process by using an air dryer in its lowest setting to melt the ice. Once the system has thawed, have a professional clean the coils. Dirty coils can not only freeze up and lead to breakdowns, but they can also cause mildew buildup.

Schedule preventive maintenance and stop problems before they start. We are here to keep you cool. If your air conditioner’s still freezing up after trying these troubleshooting tips, and you’re at the end of your rope, it’s time to call for help.

At Trust Heating and Air, we provide installation, maintenance, and repair services for all of your HVAC needs.

Contact us now, and we will be happy to get your AC up and running again.