Why does my air conditioning unit freeze up?

  • Wednesday, 27th February, 2019

Figuring out what is causing your air conditioner to freeze up can be a frustrating task, however this is not an uncommon problem. There are multiple reasons as to why your air conditioner is freezing up. It is important to address the issue as a frozen air conditioner unit will not only not cool your home properly, but can also be damaged if it continues to occur. This issue should be addressed immediately, and in this blog post we will be covering the causes behind a unit freezing up, and solutions of how to fix it.

As mentioned above, your air conditioner can freeze for a variety of reasons, some more common than others. Simply put, your unit is freezing up because something is either causing your system to make the coils become colder than normal, or something is preventing the air in your home from transferring the heat in it to the system. Regardless, this causes the evaporator coil to drop to a temperature below freezing and subsequently freezes up the unit. Here are some common causes:

1. Insufficient air flow across the evaporator coil

Air conditioning systems require adequate air flow for the cold coil. Warm air from within the home is needed to help keep the coil temperature above freezing.

2. Low refrigerant levels

This is due to lower pressure within the system. When there is less refrigerant in the system, it is still being forced to expand the same amount – more expansion means cooler temperature. As the evaporator coil drops below freezing, the moisture in the air will freeze as it comes in contact with the coil, causing ice to form.

3. Faulty thermostat and drainage problems

During the cooling process, the air conditioner condenses water vapor into liquid that drains outside. If the coil freezes, the ice will cause a blockage in the drain. The unit will still run, though will not properly cool and will also use more power.

4. Mechanical failure

If there is a kink along the refrigerant line, or a fan that is running improperly within your system this can alter the pressure and cause a freeze.

But which is it affecting my air conditioner, and how can I fix it? Inadequate air flow may be caused by dirty filter media, therefore it is recommended to check and clean the air filter regularly. It’s also an idea to check the drainpipe for any blockages, such as debris or twigs. However, some issues cannot be fixed as easily so getting in contact with a Quality Air service technician is recommended.