Why Is My AC Leaking Water Inside?

Air conditioning creates condensation. When you walk up to the car in a parking lot on a hot day and notice a puddle of water underneath it, that’s normal condensation from the AC. The same basic process happens inside your home’s system every time it runs. And just like your car, when that water doesn’t drain where it’s supposed to, you end up with a mess.

Finding water pooled around your indoor air handler or worse, dripping through a ceiling or staining drywall, is never a good thing. If you’re wondering about your AC leaking water, there are a couple of different reasons.

Where the Water Comes From

Your evaporator coil gets very cold when the system runs. When warm, humid indoor air passes over that cold surface, moisture condenses out of it, just like how a glass of cold water sweats on a table. That condensation drips off the coil and collects in a shallow drain pan.

From the drain pan, water flows out through a drain line that exits the home through a wall or routes to a floor drain or utility sink. Under normal conditions, you never think about any of this. The water appears, drains, and disappears. The problems start when the drain line gets blocked.

The Clog Is Almost Always Biological

Drain lines fail for a pretty simple reason: they’re dark, damp, and occasionally warm, which makes them great for algae, mold, and mildew growth. Water that can’t drain has to go somewhere, so it backs up into the pan. When the pan fills, it overflows onto your air handler, into your ceiling, or down your walls.

Most modern air handlers have a float switch in the drain pan for just this reason. When water hits a certain level, the switch cuts power to the system to keep the water from overflowing. If your AC suddenly stopped working for no apparent reason and you notice standing water in the drain pan, a tripped float switch is probably what happened.

Clearing an algae clog is something you can often handle yourself. A wet/dry vac connected to the exterior end of the drain line or a cup of diluted white vinegar poured into the access port near the air handler can break up early-stage buildup. That said, if the clog is stubborn, if water has already escaped the pan, or if you can’t find the drain line access point, it’s time to call someone before the water finds your drywall.

When It’s Not the Drain

The most common cause of an AC leaking water is a clogged drain line, but there are other reasons. A frozen coil will ice over while the system’s running, then melt when it shuts off. That melting produces more water than the drain pan is designed to handle in a short period, overwhelming the system even if the drain is working just fine.

The Age of Your System

Finally, an AC leaking water might have more to do with age than anything else. Over years of service, mineral deposits from occasional pan overflows, combined with corrosive interaction between standing water and the pan’s metal surface, can accelerate rust and pitting. A corroded pan can have pinhole leaks along the bottom that drip steadily and are easy to miss until the damage below them isn’t.

Don’t Wait on Water Damage

If you’ve found water around your air handler, shut the system off, soak up what you can with towels, and call for Elite. This is exactly the kind of situation our emergency repair service exists for. Regular AC maintenance can also help you prevent those problems in the first place.