Why Is Icing Bad For An Air Conditioner?

On a cold day, you might want your air conditioner to feel as cold as ice. However, if your air conditioner actually has ice on it, it is a sign of a serious problem. Here's what causes icing and what you can do about it.

What Happens When An Air Conditioner Ices Up?

If you hear the air conditioner running but don't feel any air coming out, ice is a likely cause. Ice forms over the evaporator coils when too much airborne moisture passes through the air conditioner.

When ice forms, it fills the path that air takes through the air conditioner's cooling coils. Eventually, the air flow will be completely blocked. At best, you're spending money to run your air conditioner without getting the cooling benefit, and at worst, you risk burning out the motor.

What Causes an Air Conditioner to Ice Up?

There are three common causes of air conditioner icing.

The first is running the air conditioner with a window or a door open. While you probably already know this is bad for your electric bill, you might decide to do it anyway when you're trying to get some fresh air inside on a hot day or you just get tired of letting the dog in and out.

Having a window or door open means the more humid outside air is getting pulled into your home. The extra humidity is too much for the air conditioner to handle, and the humidity turns into moisture on the cooling coils and eventually into ice.

The second most common cause is a dirty air filter. A dirty air filter slows the flow of air over the cooling coils, so the moisture that forms on them isn't wicked away as quickly, and it eventually freezes.

The other possible cause of freezing is a refrigerant imbalance. If the refrigerant levels are off, the moisture levels will also be imbalanced, and this could lead to extra water on the coils that could turn into ice.

What to Do About an Iced Air Conditioner

If you're able to determine that the cause is an open window or dirty filter, simply close the window or replace the filter. The ice will melt on its own, and you can safely turn the air conditioner back on once the ice melts.

If you suspect the problem is refrigerant or your air conditioner keeps icing up, contact a local HVAC repair contractor to schedule a repair.