Why Do I have a Frozen AC Unit in the Summer?

Having a reliable air conditioning (AC) unit in the summer is essential to find relief from the heat and ensure your comfort throughout the season. While we may not think that our AC units can fail us, malfunctions sometimes happen, including freezes. An AC unit can develop frost or ice, causing the system to stop working. If you have a frozen AC unit this summer, or you're trying to prevent it from happening to you, you should learn more about how freezing occurs below and what you can do to avoid it. Keep reading our guide for more information.

How Can Your AC Freeze During the Summer?

Many people are confused about how an AC window unit or a central AC system freezes up in the summer when it's warm outside. However, it's a more common occurrence than you might think, and it's relatively simple to explain.

Understanding how your AC works can help — your AC unit cools your home by removing heat from the house and transferring it to an evaporator coil filled with refrigerant. The coil releases the hot air outside and continues the cycle to remove heat from your home. A coil freeze interrupts this process and usually indicates a problem with your unit.

Some systems are prone to freezing when the temperature outdoors increases suddenly, more so than in other weather conditions. A frozen AC unit impacts the internal temperature and humidity levels of your home. This becomes an issue because excessive indoor humidity can cause numerous problems, including:

  • Mold and mildew growth
  • Peeling or damaged paint
  • Increase in dust mites
  • Structural damage

Some of these problems can cause worsening allergy symptoms or other health problems if a professional doesn't fix the AC unit quickly. If your AC freezes during the summer, it's essential to get to the root cause and contact an AC repair company as soon as possible to prevent humidity buildup and damage.

What Causes Your AC to Freeze?

There are a few reasons your window AC unit can freeze up in summer, leaving you without cool air when the heat rolls in. Determining the cause of a frozen AC system can help you better address the issue and get your system up and running sooner rather than later.

The following are some of the most common reasons your AC unit could be freezing this summer:

1. Airflow

If you're experiencing problems with your airflow and it's lower than it should be, the warm air inside isn't reaching the evaporator coil. When the indoor heat doesn't reach the coil, the refrigerant can't contract or warm up, causing the coil to get colder. After a while, the coil will become cold enough to freeze, preventing your AC from working.

2. Mechanical Problems

An AC unit freezing up in hot weather is sometimes a result of a mechanical malfunction. A fan can slow down or the refrigerant coil could become blocked, resulting in a freezing AC.

If you're not sure what mechanical problem could be causing your AC to freeze up, you should contact your heating, cooling and ventilation (HVAC) technician to have them conduct an inspection. Ensuring you perform regular checks and maintenance on your HVAC unit can prevent these mechanical problems, ensuring your AC unit won't freeze when you need it most.

3. Refrigerant Pressure

A frozen AC can also be caused by low refrigerant pressure. You may have a leak somewhere, which means there's less refrigerant inside the coil. A coil without enough refrigerant will have more space to expand or get colder, which can cause ice to form on the coil until it freezes the whole system.

4. Outdoor Temperature

If you've ruled out issues with your unit, it could be because the temperatures outside are too low. While it may be warm during the day, your area's temperatures could drop to 60 degrees or below when the sun sets. Your AC's refrigerant will continue to expand as usual, but in these cases, there's not enough heat to absorb. The refrigerant will expand until it freezes, meaning you could wake up in the morning to a frozen AC unit.

How to Prevent Your AC Unit From Freezing

A frozen AC unit is the last thing you want when the summer heat reaches its peak, as your unit will be unable to cool you down, allowing the temperatures in your home to increase over time. Rather than waiting to see if your AC unit will freeze, there are measures you can take to prevent it from happening, saving you time and money while ensuring your comfort through the summer heat.

1. Conduct Regular Inspections

One of the most essential things you can do for your HVAC unit is to conduct regular inspections on at least an annual basis, especially regarding your refrigerant supply. A low supply can significantly impact your AC unit's efficiency, creating a low-pressure environment where your evaporator coil will experience temperature drops below freezing, causing a frozen AC unit as ice and moisture build up.

If you think the refrigerant levels are low, you should look for a pressure gauge in your system. If you can't find one, it may be more challenging to determine if your refrigerant is the cause of your freezes without professional help. You should immediately contact your HVAC technician to refill your refrigerant supply and fix any leaks. Regular inspections ensure you won't have to deal with the consequences of a low refrigerant supply, especially in the middle of summer when outdoor temperatures peak.

You should also have your HVAC technician perform regular maintenance on your unit. Yearly maintenance ensures your system is in working order and alerts you to any minor issues before they become a bigger problem. Your technician should also tell you if any parts need to be replaced and tips to keep your HVAC unit in working order.

2. Sanitize the Evaporator Coils

One of the main reasons AC units freeze is because of dirty evaporator coils. Evaporator coils play a leading role in your AC unit's ability to cool your home, and when they're blocked by dust or dirt buildup as time passes, they won't work as they should.

When looking at your evaporator coils, you'll want to look for dust or dirt built up on them over time. Your evaporator coil is likely close to your blower fan, sometimes inside your air handler. If you're unfamiliar with the parts of your system, you may want to contact professional assistance.

You can remove dirt or dust using a gentle brush or soft towel. Use a general-purpose cleaner to help you get the buildup off your coils. You can also use the cleaner on your vents to ensure adequate airflow to your evaporator coils. You'll also want to clear your ducts of any debris buildup that could prevent proper airflow.

3. Replace the Air Filters

A hot air supply keeps evaporator coils from developing frost or ice, so it's essential to ensure they have an adequate air supply. If your air filter is dirty or clogged, it could prevent air from reaching your evaporator coils, causing the system to freeze.

Prevent this by replacing your air filters monthly or at least a few times yearly if you use premium air filters. You may need to change your air filters more regularly if you have pets or there are other sources of excess particles in your home, as these can clog your air filter more quickly.

Changing your air filter also helps your HVAC unit be more efficient because it won't have to work as hard to filter the air in and out of your home. You'll save on energy costs, and various parts of your system are less likely to become damaged.

4. Inspect the Blower Fan

The blower fan is responsible for moving hot and humid air outside so the interior of your home can cool to your desired temperature. Cold air replaces the warm air as it moves through your air ducts and out of your vents. When your blower fan isn't working or becomes damaged, the air pressure in your HVAC system is affected and can't adequately cycle air through your home.

Your blower fan can sometimes become damaged from regular use, but debris or other loose components can also cause damage. When a blower fan is damaged, it can't regulate moisture, creating a potential for it to freeze. Your fan could also be experiencing problems if your refrigerant lines are frozen.

If you've identified your blower fan as the problem, you can check to see if anything is blocking the airflow. You may need to move rugs or furniture blocking airflow from your system. There may also be debris blocking your vents. Your blower fan may also be damaged, which requires professional assistance from your HVAC technician.

If you're unsure how to check the blower fan, contact your HVAC technician to ensure they conduct a full inspection of your unit. They'll be able to tell you with certainty what's causing your unit to freeze and offer solutions to help get your AC up and running once again.

What to Do if Your AC Unit Freezes

If your AC unit freezes, there are steps you can take to get your AC unit working again so you can find relief from the heat. Do the following to narrow down the cause and find a solution:

1. Turn Off Your AC

Before looking for the potential problem, you should turn off your AC via your thermostat. Running your AC while frozen can strain your system, causing additional damage that may require repairs. Powering off your AC will give it time to thaw so you can properly look at the problem before moving forward. It's also safer to work on your AC while it's shut off, as there's less risk of electrical shocks or power surges.

2. Check Common Problem Areas

Now that your AC is off, you can start looking for the problem. You'll want to check the common problem areas mentioned above, including the air filter, evaporator coils, blower fan and refrigerant supply. Be sure to check each location so you don't miss any problem spots.

3. Determine the Cause

After checking the common problem areas, you should be able to tell what's causing your AC unit to freeze. Refer to the above section on what can cause AC systems to freeze and see whether any of those causes match up with what you're seeing.

If you're finding it challenging to identify the cause or can't get to one of the components in your system, you can always contact your HVAC technician to help you determine the problem.

4. Tackle the Problem

Once you've determined the cause of your AC unit freezing, you can move forward with fixing the problem. Each cause has a unique fix, which you can review in the sections above. If you've tried fixing the problem on your own but still find that your AC is freezing up, it could be a deeper issue with your HVAC unit.

In that case, contact your local technician to have them inspect the unit to determine the cause. Their experience and knowledge will help them quickly find the problem and offer a solution. It could be as simple as a deep clean of your unit or a system overhaul, where replacements of parts or the entire unit are necessary, as damaged or aged parts can also cause this issue.

Trust Ingrams for Your AC Needs

A frozen AC unit in the middle of summer is inconvenient, causing you to sit in warm temperatures while you try to solve the issue. Sometimes, the cause of your AC unit freezing is damaged parts or an old AC unit that's outlived its usefulness. If you're in the market for a new AC unit to help you find relief from the heat, Ingram's Water & Air is here to help.

Our products are more affordable than units you might find from your local HVAC servicer. We also provide technical assistance for maintenance and installation to ensure your HVAC unit continues working through the warmest months. Browse our selection of HVAC products today to get started!

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