My Central Air Freezes When the Temperature Gets Above 95 Degrees

Airflow Restriction

• A high temperature alone will not cause ice to form, but an airflow restriction may prevent enough air from passing over the coil to dry out the moisture before it freezes. And once the airflow has been restricted and ice begins to form, the problem grows and grows. Airflow restriction in your central air system can result from dirty air filters that choke off the air going through the system. It can also be caused by debris blocking the air intakes at the outside unit. This may be because of plants that have grown up around the unit, dirt and lawn clippings clogging the intakes, or lawn furniture that is stacked next to the intakes. Make sure the area around your unit is clean and that the air filters are changed regularly.

Cooling Fins

• The cooling coil in your outside unit has a very fragile metal component called fins that allow the air to move efficiently across the coil itself to create cold airflow. These fins can easily be crushed or bent. When the cooling coil fins get damaged they can block enough of the air from the evaporator to make ice form because of the high level of moisture. There are special tools available to straighten out these damaged fins.

Blower Fan

• The blower fan is the fan that forces the air across the coil and pushes it into the ducts in your home for cold air distribution. If this fan is excessively dirty or has stopped working because the motor has malfunctioned, it could potentially cause freezing on the evaporator coil. See to it that the blades of the fan are kept clean and that it is running normally when the central unit is in use.

Refrigerant

• Contrary to logic, if your central air conditioner is low on refrigerant, it can make it too cold. Although the refrigerant is the gas responsible for creating the cool air, too little of it will make the coil overcompensate and get very cold to the point that ice forms on the evaporator. Since an air conditioner does not actually consume refrigerant like a fuel, a low charge indicates a leak. Have a professional recharge your system after repairing the leak.