Ice on the AC / Heat Pump Outdoor Condenser, Refrigerant Lines, or Indoor Coil

There are a few reasons why an air conditioner might freeze. Here are the most common ones:

• Low refrigerant levels. Refrigerant is the key to an air conditioner’s cooling process. It absorbs heat from the air and then carries it away to be released outside. If the refrigerant levels are low, the air conditioner will not be able to remove enough heat from the air, and the Indoor evaporator coil will start to freeze. (ice over)
• Blocked airflow. The evaporator coil needs to have a constant flow of air over it in order to work properly. If the airflow is blocked, the coil will not be able to cool down, and it will start to freeze. Common causes of blocked airflow include dirty filters, clogged ducts, and obstructed vents.
• High humidity. When the air is humid, it contains more water vapor. This water vapor can condense on the evaporator coil, and if the coil is not able to get rid of the water vapor, it will start to freeze.
• Refrigerant leak. If there is a leak in the refrigerant lines, the refrigerant will slowly leak out of the system. This will cause the refrigerant levels to drop, which can lead to the evaporator coil freezing.

If your air conditioner is freezing, it is important to find the source causing the issue. If it’s something simple like a very dirty filter, replacing the filter with a new clean one is an easy remedy. Other issues like a leaking evaporator coil will require coil replacement or a repair if the leak is fixable. It’s important to have it repaired as soon as possible to minimize damage to the compressor and fan motors. A frozen air conditioner is not only inefficient, but it can also damage the unit.