What Causes Air Conditioners to Freeze Up?

During the warmer seasons when your air conditioner is running on full blast, you might notice something peculiar on the exterior side of the unit: ice. Air conditioning units are designed to cool the inside of the house -- so, why does the outside look like the inside of a freezer?

If you’re wondering why blocks of ice have built up around your air conditioning unit, we’ve rounded up the common reasons why air conditioners freeze up.

#1 Low Refrigerant

Air conditioners (ACs) use the refrigerant called chlorodifluoromethane or R22, or R410A. As the liquid cycles through your AC, it turns into a gas and absorbs heat, allowing your AC to produce cool air. When refrigerant levels run low due to leakage or evaporation, the moisture that it was supposed to cool turns into water and drips into the drainage pan. Eventually, the water will reach the evaporator coils and become blocks of ice.

When this happens, turn off your AC unit and allow the ice to melt naturally. The refrigerant can then be replaced by a professional HVAC technician. Keep in mind that the U.S. Environmental Protection Agency (EPA) does not allow homeowners to “top off” the refrigerant by themselves.

#2 Poor Air Flow

Without enough air, your AC won’t be able to prevent moisture from turning into ice. Cool air will stay on the evaporator coils and the unit’s temperature will begin to drop. As a result, ice will build up around the AC, freezing up the entire unit.

To prevent restricted airflow, make sure to replace the air filters regularly. Over time, these filters will trap dust, dirt, and other contaminants. Too much buildup can result in poor airflow. You should also check whether the evaporator coils and fins have been clogged up. In this case, the best solution would be to have the evaporator cleaned by a qualified technician

#3 Low Temperature and Fan Settings

Avoid running the AC with both the fan and temperature settings too low. This causes the coils to freeze up. As a rule of thumb, the air conditioner’s fan should be on medium or high, as this allows air to flow efficiently through the coils. Only set the fan mode to low if it’s unusually humid outside. Air conditioners on low fan settings double as dehumidifiers.

Your AC may also freeze as a result of setting the AC’s temperature too low. Ideally, air conditioners should be set at around 68 degrees Fahrenheit.

#4 Broken Blower Fan

Your AC’s blower fan is an essential component. It “sucks” hot air and pushes out cool air. When the blower fan breaks, this significantly impacts the airflow inside of your air conditioner. Condensation will build up between the evaporator coils, and the water will soon turn into ice.

What to Do if Your AC Freezes

The moment that you notice ice building around the exterior of your air conditioner, turn the unit’s thermostat off. Then, put it in fan mode, letting the air slowly melt the ice. Call an HVAC repair service to prevent further damage to your air conditioner. There are certain issues that only qualified technicians can address, such as replacing the refrigerant.

A frozen air conditioner can easily be fixed, but only if you have it checked and repaired immediately.

Call Your HVAC Company Today

If your heating and cooling system requires replacement, reach out to your local HVAC company. They can explain to you the benefits of installing a new HVAC unit, as well as offer the most accurate pricing for the costs for installation.