You want your air conditioner to supply cold air all summer long, but sometimes you can have too much of a good thing! Frozen evaporator coils are a typical failure mode for air conditioning systems, and they can be a frustrating one when you're trying to beat the heat. Many homeowners also misunderstand what's happening when their AC freezes and may even make the problem worse.
What Really Happens When An AC Unit Freezes?
Your air conditioner acts as a heat transfer system. The evaporator coil in your home collects heat and utilizes refrigerant to transport that heat to the outdoor condenser coils. As the air around the coils cools, it releases moisture in the form of condensation. When your AC is operating normally, this moisture collects on the coils and runs into a drain pan.
AC system designs prevent temperatures near the evaporator coil from becoming so cold that this condensation freezes. If something causes this to change, ice can form on the evaporator coil. This ice can insulate the coils and prevent them from transferring heat to the refrigerant. As a result, the refrigerant doesn't undergo a phase shift, and the liquid refrigerant may return to the compressor.
Why Shouldn't You Use a Frozen AC?
Air conditioners typically don't freeze up as soon as you turn them on. Instead, ice slowly builds up on the coils until the compressor can no longer push refrigerant through the system, causing your AC to lock up and shut down. Modern air conditioners include various safety switches that keep your unit from operating under these conditions.
Unfortunately, safety switches may not be enough to avoid damage. A frozen evaporator can stress numerous components in your system, including the compressor. Continuing to run your air conditioner while you know it's freezing can result in excessive wear on the compressor and shave years off of its life.
What Should You Do With a Frozen AC Unit?
Two of the most common causes of evaporator coil freezing are poor airflow and refrigerant leaks. While you shouldn't address a refrigerant leak yourself, you can check for a clogged or obstructed filter. If you haven't replaced your filter in a while, try installing a new one and see if that solves the problem. You should also check for obstructions near vents that may be restricting system airflow.
If these straightforward solutions don't get your system running again, it's time to call in a professional. An air conditioning contractor will check the condition of your blower motor and your refrigerant levels, allowing them to zero in on the underlying cause. Avoid using your system in the meantime to ensure that you don't cause additional damage to your compressor.
