Why is Ice Forming on the Inside of My Air Conditioning (AC) Unit?

You’re concerned. Your central air conditioning isn’t cooling your home very well. So you go to check your equipment and discover ice on the inside unit of your air conditioning (AC) system. You may find this issue strange considering it’s summer.

What Causes an Air Conditioner (AC) to Freeze Up Inside?

What could be the problem? There are 2 main issues causing this. Read on to learn what they are and what to do about them or reach out to a professional to receive assistance with the issue.

1 – Weak & Reduced Airflow Over the Evaporator Coil

Reduced airflow to the inside unit will cause the refrigerant coil to freeze up. First, we will tell you what usually causes reduced airflow to the inside unit and then explain the science behind why reduced airflow would cause the unit to freeze up.

Why Restricted Airflow Causes the Coils to Freeze Up

The evaporator coil, tubes forming the A-shaped part of the inside unit, has cold refrigerant flowing through it. A blower pulls in air from your home and over that coil, cooling the air in your living space.

However, when there is little to no air flowing over the cold evaporator coils, your air conditioning (AC) unit will freeze up and excess ice will form on the coils. When it’s frosted over, air can’t easily flow through the coils because it’s a solid block of ice, reducing airflow to your home.


2 – Low Refrigerant

This is the most common cause of a frozen evaporator coil. When your AC system is low on refrigerant, the pressure drops causing the evaporator coil to get abnormally cold.

So when returning air hits the coil, humidity/moisture from the air beads ups on the coil and quickly freezes. This continues until the evaporator coil is frozen. If you’re low on refrigerant you also have a refrigerant leak. That means you will need a professional to find the leak and fix it before adding more refrigerant.

If the inside unit of your air conditioning (AC) system continues to freeze up after you have replaced the air filter and adjusted your vents, you will need to call a professional to resolve the issue.

Call EFE Home Service now and we will send you our experienced technicians to fix your problem. 610-533-1278


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