How to Keep Your AC From Freezing in the Summer

  • May 26, 2023
  • By MR COOL

Have you ever wondered why your heat pump freezes up in the summer? While it seems strange to imagine anything freezing in the heat of summer, AC freezing is a real concern for homeowners.

From small issues like a blocked vent to bigger concerns like broken components, there are several ways to identify and prevent your AC from freezing. Learn more about the causes and prevention methods for a frozen AC below.

What Causes an Air Conditioner to Freeze Up in the Summer?

Your air conditioner can freeze even during the warm summer months. There are a few potential causes of a frozen air conditioner, including:

  • Low refrigerant levels: The refrigerant in your AC system is what keeps your home cool, but it can also lead to freezing up your entire unit if the refrigerant levels are too low. Low refrigerant levels are commonly caused by a leak somewhere in your system. Improper refrigerant levels make it hard for your AC unit to regulate the temperature accurately, which then causes your AC to freeze.
  • Dirty or clogged air filters: Your AC system needs proper airflow to work. Clogged or dirty air filters reduce the amount of airflow in the system, which can trap the cold air and cause the AC unit to freeze.
  • Broken coils: Dirty or broken coils prevent the coils from doing their job — absorbing heat. Without heat, these coils will eventually begin to freeze.
  • Broken thermostat: If you have a broken thermostat, you can’t control your AC unit’s temperature. This can leave your system exposed to constant cold air, and the unregulated air temperature can then lead to the system freezing.
  • Broken or poorly running fan: Another airflow issue comes from broken or slow fans. This fan regulates the AC coil’s temperature, and without a properly functioning fan, moisture will form and eventually freeze once it comes in contact with the AC refrigerant.
  • Blocked or closed vents: The cold air your AC unit is producing needs to be able to leave the system. If vents are closed or blocked, the cold air will be trapped inside the AC unit, making it more likely for ice to form.
  • Old age: If your AC unit consistently freezes, it may be a sign that your unit as a whole is old and in need of a replacement. Over time, your unit will wear down, making it more likely for the issues above to occur.

How to Stop Your Air Conditioner From Freezing in Hot Weather

You now know what causes air conditioners to freeze, but how do you keep your AC from freezing in the summer? With a few quick inspections and proper maintenance, it can be quite simple to prevent your AC system from freezing. Check out some of the top tips for preventing your AC from freezing up in hot weather below.

1. Check Refrigerant Levels

Low refrigerant levels are usually an indicator of a refrigerant leak. Refrigerant leaks can lead to ice buildup on your air conditioner.

Leaking refrigerant won’t stop your AC unit from running. Instead, the temperature of your coils will drop below freezing due to the lack of refrigerant. With coils this cold, water vapor will freeze on the coil’s surface. If this continues, your coils will go from having a light frost to a thick coat of ice, which can become a serious problem.

Leaks can occur on the refrigerant lines, evaporator coil or compressor. It’s best to have an HVAC technician inspect your AC system’s refrigerant levels and locate any potential refrigerant leaks.

2. Clean or Replace Your Air Filter

Dirty air filters can lead to limited or blocked airflow. If your AC system’s evaporator coil isn’t getting enough airflow through the air duct, ice will eventually begin to form along the coil. Luckily, this can be prevented, as you should be inspecting and changing or cleaning your air filter routinely regardless. A clean air filter helps improve your air conditioner’s performance as well as improve your air quality.

You should clean or replace your filters every one to two months. However, during frequent AC use periods, such as the summer, you’ll want to check your filters more often to ensure proper airflow.

3. Inspect the Drain Line

As your AC system works to cool down your home, moisture condenses out of the air. Your AC system has a dedicated condensate drain line to help remove this liquid, but this drain line can become clogged and overflow. As the overflowing water comes in contact with your evaporator coil, it will begin to freeze.

If you suspect blockages in your drain line, a wet/dry shop vacuum can help remove any debris and keep your AC unit from freezing up in the summer.

4. Keep Your Vents Open

Ensuring your vents are open and free of any potential blockers like furniture is an easy way to prevent your AC system from freezing. Blocked or closed vents can lead to airflow issues, which then leads to your AC system freezing. In general, you should avoid closing more than two to three vents at a time. 

5. Ensure the Fan Is Working Properly

Your AC system’s blower fan generates the airflow needed to keep the evaporator coil from freezing. A low-functioning or broken fan will severely impact the system’s airflow and can lead to the system freezing up. It’s best to have an HVAC technician inspect your fan to ensure everything is functioning properly.

Should You Repair or Replace an Air Conditioner That Freezes Up?

It’s best to have a professional HVAC technician inspect your AC unit to determine the cause and course of action for your frozen AC. Your AC may have a small issue that can easily be repaired to get your system back to normal. In other cases, an inspection may show it’s time for a full system replacement. Older AC units are more prone to experience issues that cause AC freezing, so if you have an old unit, you’ll want to consider a replacement system.

In the long run, a new system will save you money due to fewer repairs and better efficiency, and you’ll have peace of mind that your AC works properly. Consult your local HVAC technician to review your options and see if repair or replacement is the right choice for you.

Trust MRCOOL for All of Your AC Needs

If your frozen AC unit is beyond repair, MRCOOL’s high-quality AC units can help. Choose from a variety of great options, like the MRCOOL DIY Ductless Mini-Split, to keep your home comfortably cool. Our expert team and various MRCOOL dealers across the country will be able to help you find the right cooling solution for your home.

For more tips and information, visit our MRCOOL blog.

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