Why Is My AC Leaking Water Even Though It's Not Running Much Anymore?
Even as the weather cools and you're relying on the AC less, a water leak from your indoor unit or around your furnace (where the AC's evaporator coil usually sits) doesn't just go away on its own.
Why leaks happen even with light AC use
A clogged condensate drain line. As your AC cooled your home all summer, it also pulled moisture out of the air, which drains out through a condensate line. Algae, dirt, and debris build up in that line over the season, and even occasional AC use can be enough for water to back up and overflow once the line is sufficiently blocked.
A cracked or full condensate drain pan. Pans corrode and crack over years of use — even light, intermittent use can be enough for water to escape through a crack rather than draining properly.
A frozen coil that's now thawing. If the system ran with low airflow or low refrigerant this summer, ice may have built up on the evaporator coil. As the system runs less and that ice melts, it can produce more water than the drain system is designed to handle at once.
Improper condensate pump function, in systems that rely on a pump rather than gravity drainage.
Why this matters even in cooler weather
What you can safely check yourself
What you can safely check yourself
Look at the area around your indoor unit for water stains, dampness, or a musty smell. Check that the condensate drain line isn't visibly clogged or disconnected near where it exits the house.
When to call a professional
If you see active leaking, staining, or a musty smell, or if this is a repeat issue from earlier in the season, have it inspected before the coil area is buried under a running furnace all winter.
When to call a professional
Air 1 Mechanical offers 24/7 emergency AC repair — call (703) 360-4357.
