3 Common Things That Could Be Causing Your AC Unit to Freeze Up

A frozen over outdoor AC unit


Typically, ice will start forming on the copper lines that come out of the system before you will see ice building up on the unit. Sometimes the frost can be so bad that full blocks of ice form. Don’t panic, ice formation isn’t always a sign of serious issues but it is a sign that you cannot ignore. After noticing any ice formation, you should turn your AC unit off or turn up your thermostat so the unit goes into heat mode, defrosting the ice that has built up.  Here are the top 3 causes and solutions:


If your AC system is low on refrigerant or charged incorrectly, the coils can become too cold.  As the moist, warm air from your house moves over the evaporator, the moisture will condense and freeze on the coils and ice will begin to form.  This problem is handled best by a professional HVAC technician, they can perform a diagnostic test and look for the potential causes and address the issues. 


Your AC unit needs to receive the proper airflow to prevent the condensation coil from icing up.  This requires the unit to have enough warm air from your home pass through the system to prevent the lines from freezing over. Dirty air filters can prevent the proper air exchange and can lead to issues with the icing of units.  Check and replace dirty air filters and may sure all air grates are open and no furniture is blocking your ducts.  If your air filters are clean and your grates/ducts are open, it might be time to contact a professional HVAC technician for an AC Tune-Up


Evaporator coils not only help cool your house but they also help pull the humidity out of your house.  As they pull the water out of the air, this makes condensation build-up on the coils and normally the droplets fall into the drip pan.  If the drip pan is overflowing, the coils can become waterlogged and start to freeze.  In addition, if the coils are dirty, the coils can begin to freeze as the dirt on top of the coils can prevent them from absorbing the water fast enough.  Having bi-annual HVAC maintenance from a professional HVAC tech can keep your coils clean and free of dirt.

Time to Call the Experts

When you see ice forming on your unit or lines, it may be time to have a professional inspect your entire system. The pros at Dependable Service Plumbing & Air can fix it for you. Contact us so we can keep your HVAC system running as efficiently as possible.