If your AC isn’t working properly and you notice frost or ice on the indoor unit, this means the AC coils are frozen.  However, even if you don’t notice ice or frost on the coils, it could still mean there is an issue.

Symptoms of frozen coils include no cool air or warm air blowing from the registers or no air blowing from the registers at all.  Additionally, a build-up of moisture can cause condensation or water leaks in your home.

If you suspect your AC coils have frozen, here are 4 of the more common reasons the coils have frozen.

1.    Dirty Air Filter

A dirty air filter can prohibit air flow through the unit, which then obstructs air from getting in and out.  The lack of air circulation around the coils means the coils will get too cold, leading to accumulating ice.

Maintain good air circulation by changing your air filter regularly.  For basic air filters up to 3 inches, manufacturers recommend replacement every 30 to 60 days.

2.    Broken Fan

Even if the air filters are clean and changed regularly, if the fan isn’t working properly it could lead to frozen coils.  Lack of air flow because of a broken fan motor or dirty fan blades will cause coils to freeze.

Schedule bi-annual maintenance on the HVAC system in the fall and the spring to ensure the unit is clean, the blades are not dirty, and the mechanics of the system are in good working order.

3.    Faulty Thermostat

The thermostat works with the AC by checking the temperature and controlling how hard the AC needs to work to keep the temperature consistent.

If the thermostat is broken, it will sense the wrong temperature and can cause the unit to run too long and wear out the system.  If you have trouble keeping your home at a consistent temperature or see the AC running too cold there may be an issue with the thermostat.  When left unchecked an overworked AC could develop frozen AC coils.

If you notice this issue before there is a problem with the HVAC system, or if your thermostat is very old, simply replacing the thermostat can avoid further issues.

4.    Blocked Condensate Lines

The condensate lines are the part of the HVAC system that drains the excess moisture from the humidity.  This moisture is condensed into water and drained out of the system into the floor drain.

When water gets stuck in one place due to a clogged pipe it can cause the coils to freeze.  The evaporator coil is the coldest part of the AC, when the water gets stuck it will cause the coils to freeze.

Bi-Annual maintenance to ensure everything is clean, clear, and running smoothly can help to prevent blocked condensate lines.

Frozen Coils

If you have determined that your AC coils are frozen shut of the unit.  Shutting off the unit will avoid even more complications, like compressor failure.

Find and clean up any water damage.  Attempt to melt the ice, simply turning the system off and letting the freeze thaw on its own or use a hair dryer.  Never chip or cut the ice, you can damage the coils.

If you have thawed the frozen coils and your unit still will not work, give TR Miller Heating and Cooling a call and we can have one of our experienced technicians help you.

An Ounce of Prevention is Worth a Pound of Cure

A biannual maintenance plan can help avoid any problems.  Preventative maintenance with a fall and spring inspection and system check by an HVAC specialist is recommended to keep your HVAC system running smoothing and can assist in avoiding any surprise repairs or emergency service in the future.

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