Why is My Air Conditioner Freezing Up?

Air conditioning units are supposed to cool the temperatures down, but they can also become too cold and freeze up. While this may sound odd, it's true and there are a number of reasons why your AC unit might freeze up. Below are some of these reasons.

  1. Blocked Air Flow

AC units require a consistent flow of air to keep humidity from settling on the coils and freezing. To keep your home's air flow moving enough to not interrupt the functionality of your air conditioner, you must check the air filters regularly to ensure they're not dirty or clogged. If they become clogged and dirty, it could restrict your home's air flow. You should regularly change them. Another way of preventing air flow issues is by keeping your air conditioner tuned up and clean.

  1. Low Refrigerant

Sometimes, air conditioner freeze ups could be due to the refrigerant R22 (chlorodifluoromethane). R22 refrigerant has distinct physical properties at a variety of pressure levels. When your unit is functioning properly, the refrigerant passes through the lines at a temperature that condensation could form on the line on the outside.

If your system's pressure changes, this could make the R22 work differently. As the warm, moist air from your home flows over the evaporator, it will cause the moisture to condense, freezing on the coils, causing ice to form. You may see a change in your system's performance with minor frost, but when there's too much ice, it can impact the airflow.

Gradually, the ice will work like an insulator, preventing the AC unit from properly functioning and the R22 refrigerant will quickly evaporate. When the level of refrigerant becomes too low, the AC unit can't freeze the line. Then, the ice might melt and you'll see the air flow's behavior has stopped, but the system isn't doing any cooling.

When your system doesn't cool anymore, this could indicate your air conditioner has potential water damage. You'll want to call an HVAC expert in to come check it out and repair it as soon as possible.

  1. Closed Air Registers

Because closed air registers can stop airflow, you should check the registers and make sure they're open and clear.

  1. Drainage Problems and Faulty Thermostats

Drainage issues and faulty thermostats are frequent causes of a freeze up. During the cooling process, the air conditioner condenses water vapor, turning it into liquid that drains outdoors. When you have frozen coils, the ice will cause a drain hole blockage. Your air conditioner will still operate, but it won't cool your home properly and it will use a lot more electricity. Be sure you check for blockages in the drainpipe like twigs and debris.

In some climates, all you need is a whole house fan. A whole house fan provides effective indoor home evening cooling when temperatures outdoors are cooler than indoors.