Help! My AC Evaporator Coil Is Frozen 

The first indication that your AC evaporator coil is frozen may be a feeling of discomfort – your AC is on, but it’s blowing warm air instead of cold. When you go looking to see what the problem is, you see one or both of the following telltale signs of a frozen evaporator coil: 

• Visible icing of the evaporator coil or its cabinet 
• Frozen refrigerant lines at the outdoor unit 

You may also see puddles of water on the floor if the frozen AC coil is thawing out. 

We recommend shutting your AC system off. Go to your thermostat and switch it from COOL to OFF. This is because running the system with a frozen coil can cause major damage to your air conditioning system. 

DO NOT chip away at the ice. This can damage the coil. Call your HVAC company to get on the AC repair schedule. 

Schedule AC Repair Now

Before understanding why the evaporator coil froze, you need to understand a little about how it works. The evaporator works with other air conditioner components during the refrigeration cycle to cool your home.  

Specifically, the evaporator coil is cooled by expanding liquid refrigerant. During this process, the coil absorbs the heat from your home and turns the refrigerant back into a gas before sending it back out to the compressor.  

As the indoor unit blower fan blows air across the coil, the air is cooled and then sent into your ductwork system and distributed throughout your home.  

The biggest reason for an evaporator coil to freeze is restricted airflow. This can be caused by: 

• A clogged or dirty filter 
• Blocked return air vents 
• Dirty evaporator coil 
• Low refrigerant 
• Thermostat issues 

When the HVAC technician arrives, they will check for all the possible causes of your frozen AC coil. If the filter is clogged, they will change it. If the coil is dirty, they’ll clean it. They may also troubleshoot your thermostat if they think it’s part of the problem. 

They will check the refrigerant levels and test for a refrigerant leak. That’s because the only way you would have low refrigerant is if there was a leak or the unit was improperly charged when it was installed. If they find an obvious leak, they will try and repair it. Lastly, they will recharge the refrigerant if necessary.  

Your air conditioning repair costs will vary depending on what caused the AC coil to freeze.  

You can help prevent a frozen evaporator coil and other problems with regular air conditioner maintenance. Some you can do yourself and other work should be left to an HVAC professional. 

Change the AC filter every 1-3 months based on the quality of the filter. Your thermostat may display an alert when it’s time for a filter change. Otherwise, set a calendar alert on your phone. See our HVAC filter maintenance guide for tips.  

Keep your air vents clear. Keep the floor around the indoor unit clean and sweep away dirt, dust, and cobwebs. Keep landscaping at least two feet away from the outdoor unit to promote air circulation.  

Schedule an AC service visit every spring to help your AC run at peak performance all summer long. The HVAC technician will inspect the unit, clean the AC coils, and more. A yearly visit can help spot issues while they are still small and before they lead to high AC repair costs. Sign up for their HVAC service plan and they will reach out to schedule appointments each spring and fall. 

Finally, think about opting into Trane Diagnostics. This allows your Trane dealer to monitor your HVAC system remotely. They’ll receive alerts of any system issues and can act quickly to help you, even when you’re away from home on vacation. 

Anne Fonda, Content Writer at Trane Technologies

A Content Writer with Trane Technologies, Anne Fonda researches topics and writes for Trane® and associated residential HVAC brands. She works in collaboration with Trane Technologies subject matter experts, offering easy-to-understand, informative content on complex topics. Her goal is to help consumers make informed decisions on the products and services they need.

She has written for HVAC and other service provider websites for over 16 years. Before transitioning to web content writing, Anne had a 14-year stint as an award-winning journalist. She graduated cum laude from the University of Missouri-Columbia School of Journalism. When she’s not working, Anne enjoys playing word games, reading, gardening, spending time with family, and visiting gardens and museums.

Expert review by Kimberly Sexton, Senior Systems Engineer

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