Evaporator Coil Troubleshooting: What to Do When It’s Frozen

Evaporator Coil Troubleshooting: What to Do When It's FrozenThe evaporator coil carries the chilled refrigerant that’s responsible for removing the heat from your home in order to provide cooling. Normally, it works as it should, but periodically, you may find you need tips for troubleshooting a frozen evaporator coil to restore it to full functionality. 

Dirty Air Filter

A dirty air filter slows the passage of air over the evaporator coil, leaving it too cold. As the humid air from your home passes over it, the water vapor may freeze instead of condense. Eventually, the entire coil will be covered with frost, and all cooling in your home stops. If you notice that your home isn’t cooling, check the air filter first and change it if it’s dirty.

Thaw the coil by turning the system off, but setting the thermostat so the fan is on. It will pull warm indoor air over the coil to melt it. If you don’t have an “On” setting, use a blow dryer pointed at the evaporator coil to thaw it. If the problem soon reoccurs, ask your HVAC technician to thoroughly clean the components inside the air handler, including the coil.

Low Refrigerant

Troubleshooting a frozen evaporator coil caused by low refrigerant requires an HVAC technician. The U.S. EPA restricts access to refrigerant; only licensed contractors can handle it. If the filter is clean and you haven’t had your system professionally maintained recently, you may have a leak that needs to be fixed.

Clogged Outdoor Condenser

The condenser needs ample airflow through it to remove the heat from the refrigerant before it reenters the compressor and back to the evaporator coil. If anything is blocking it, the airflow will slow. The condensing coil and fins may also be dirty. Hose them off and use a soft brush to remove any dried vegetation or grass clippings.

If you’d like professional help troubleshooting a frozen evaporator coil, contact Davis Air Conditioning. We’ve been helping southwest Oklahoma homeowners with their HVAC systems since 1976.


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