Regular Air Conditioning Maintenance Can Prevent Frozen Coils

Although rare, there may come a time when your air conditioning unit seems to be slow at cooling the home or isn’t cooling at all. If ice is visible when looking at the lines going into the unit, it is an indication that something is not right. It may not be something major, and is usually caused by a clogged air filter, but the unit needs to be turned off.

If the fan can be heard running, simply turn it off and wait for it to thaw out. If the fan is not running, turn the unit off and then switch the thermostat from automatic to on and let the fan blow warm air through the system until the lines are defrosted. Do not turn the unit back on until all of the lines are completely thawed.

Understand that these methods will get your unit back up and running, but they may not solve the underlying issue that caused the coil to freeze in the first place. As stated, it is usually a dirty air filter that interfered with air flow in the system that caused the frozen coils. Pull out the air filter and if it is dirty, replace it with a new one. If the unit has a washable filter, take it out and rinse off the screen and return it into place.

While filters are usually the culprit there can be other reasons for reduced air flow across the coils allowing them to become coated with ice. The system is equipped with a blower, sometimes called a fan that is located somewhere between the air filters and the evaporator coils. Even with regular air conditioning maintenance and filter changes dust and dirt can still get into the blower motor, blocking air flow through the motor cage, and be deposited on the fins of the fan.

This is more common if the wrong sized air filters are used or if they are not seated properly allowing dust to get around the filter. When replacing the filters ensure they fit tight at the edges. Some units will have a foam edge on one or more sides to ensure the filter is sealed all the way around.

Never use a sharp or rigid object to chip away the ice built up on the coils or lines. This can cause severe damage to the lines and can be costly to repair. It will take time for the ice to melt and while waiting is the time to check the filters. If the problem persists with no obvious signs of air flow restriction it will be best to contact an experienced air conditioning servicetechnician to get to the bottom of the icing problem.

If your home has a heat pump and the system is frozen, it can be turned to the heat mode to help thaw things out faster. In addition to a lack of air flow across the evaporator coil causing them to freeze, another cause can be a problem within the refrigeration system.

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Jamie Brock profile image

Jamie Brock 4 years ago from Texas

We actually had this problem a lot in our old apt...I'm so glad to be out of there! The A/C would freeze up constantly... so we were half the time waiting on it to un-thaw so we could turn it back on again. Thanks for sharing.. will keep this stuff in mind if we happen to have any problem like this in our new place.

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