AC Leaking Water

Is your central AC system leaking water? Don’t panic. Learn what is causing the problem and what you can do about it. Visit our ductless mini-split troubleshooting page if the issue is with your ductless system.

There are several causes for an AC unit leaking water inside. In a standard split system, your air conditioning system consists of an outdoor condenser unit with a condenser coil and an indoor coil called the evaporator coil. The two components are connected by refrigerant lines and together, they complete the refrigeration cycle that cools your home.

This cycle generates condensation. When everything is working as it should, the condensation drains away from the indoor unit. If you see a puddle of water near the unit, there’s a problem.

There are 4 main reasons your central AC is leaking water inside.

We mentioned the condensation created by the refrigeration cycle drains away. The condensation first drips into the AC drain pan. Over time, the drain pan can corrode or crack, allowing water to leak onto the floor near the indoor unit.

This can cause water damage if left unchecked. The drain pan can also get filled with dust and debris, causing it to overflow.

When the drain pan is intact, the water it collects is directed at a downward slope to the AC condensate drain line. This is a PVC pipe that goes from the indoor unit to outside your home where it releases the water. With time and lack of maintenance, the AC drain line can become clogged with mold, mildew, dust, spider webs, etc.

An AC drain line clog can cause water damage, a musty smell, and other issues.

A frozen evaporator coil can also cause a puddle of water near your indoor unit. The evaporator coil can frost over or freeze for several reasons, nearly all of which are preventable. Regular filter changes and professional air conditioning maintenance can help you avoid a frozen coil.

If you have a frozen evaporator coil, call an HVAC professional now.

Lastly, a problem with the outdoor condenser unit can result in a puddle of water at the indoor unit. (Remember the indoor and outdoor coils are connected.) Years of wear and tear can cause the condenser to malfunction and can also cause a refrigerant leak.

If you see that your AC unit is leaking water, we recommend turning it off and calling for AC repair. Continuing to run the AC without fixing the problem that caused the leak could cause damage to the system.

You can help prevent your air conditioner from leaking water or exhibiting other issues by taking care of the unit with regular maintenance. This includes changing the air filter every 1-3 months based on the filter. Something as simple as a clogged or dirty air filter can cause some big problems. See our HVAC filter maintenance guide for tips.

Keep the area around the indoor unit clean and sweep away dirt, dust, and cobwebs. Keep landscaping at least two feet away from the outdoor unit.

Schedule an AC tune-up every spring for optimal performance and to catch problems while they are still small and before they lead to increased AC repair costs. Ask your local HVAC company if they offer a service plan. Most do.

Finally, consider opting into Trane Diagnostics. This allows your Trane dealer to monitor your HVAC system remotely. They’ll receive alerts of any issues with your system 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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