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Your Indianapolis Licensed HVAC Contractor


Your Indianapolis Licensed HVAC Contractor


Vital Heating & Air Blog

Ice on Your Air Conditioner Isn’t Normal


This is one of the most common misunderstandings people have about air conditioning systems: seeing ice developing along the indoor evaporator coil is normal. Maybe the AC is working a bit too well, but what’s so bad about that?

The truth is much different. You should never see ice forming on the evaporator coil or any other part of an AC. An air conditioner doesn’t use ice to cool the air. It provides cooling by removing heat from the air and moving it outside. However, because people still imagine frost growing inside old freezers, they tend to imagine that ice on an AC isn’t a problem. 

So why does ice start to appear on an AC and what does it mean? Below we’ll explain the ice problem and why it usually means you need professional AC service in Indianapolis, IN.

Ice means the evaporator coil isn’t absorbing enough heat

This is the basic reason ice starts to form on the evaporator coil. The way the coil cools down the air is that freezing cold refrigerant moves through it and evaporates as it meets the warm air sent across it. The refrigerant absorbs heat as it evaporates, which cools the air at the same time it warms the refrigerant, raising it above freezing temperatures. 

If something prevents the evaporator coil from absorbing enough heat to raise the refrigerant temperature above freezing, the coil will stay so cold that water moisture along it will freeze. And once ice starts to appear, it becomes a snowball situation: the ice will further block heat absorption and more ice will grow until the coil is completely blocked and the AC won’t be able to cool the air. 

Why the coil may not be absorbing enough heat

Now we know the basic cause for ice appearing on the evaporator coil. But what prevented the coil from absorbing enough heat in the first place? There are several culprits:

  • Clogged air filter: Clogged air filters can cause numerous problems, and this is one of the biggest. If the filter prevents proper airflow through the AC, there won’t be enough warm air moving across the coil to allow it to warm up the refrigerant. 
  • Dirty evaporator coil: The coil may have dust, grime, or mold on it. All will serve as a thermal barrier preventing proper heat absorption and lead to ice on the coil. 
  • Low refrigerant: This is the most serious problem and one that can confuse people. Why would less refrigerant cause ice to form? It’s because less refrigerant in the coil means less heat can be absorbed, meaning that the remaining refrigerant stays far colder. Low refrigerant can happen because of leaks, and it will eventually jeopardize the entire air conditioning system. 

Call the professionals 

If you see ice forming along the coil of your AC, call our technicians to see what’s wrong and repair it. Even if it’s just a clogged filter, you’ll need us to help with defrosting the coil. (Don’t attempt to scrape off the ice yourself, you may damage the coil.) Refrigerant leaks are particularly urgent and require that we seal the leaks and then add the proper amount of refrigerant to restore the system to its original levels. 

Rely on Vital Heating & Air Because “Your Comfort Is Vital!”

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