AC Leaking Water in Dallas: The Attic Drain Problem and How to Fix It

Most DFW homes have the air handler in the attic. In humid summer air, the coil pulls a lot of condensate. The drain line runs to the outside, and the warm, wet pipe grows algae that eventually blocks it. The primary pan fills, and either the float switch shuts the system down or the pan overflows into the ceiling below.

The secondary drain, a separate pipe that often exits under an eave, is the warning sign. If you see water dripping from a small pipe near the roofline, the primary drain is clogged and the backup is doing its job. Act before the backup overflows too.

Freeze-ups compound it. When a frozen coil thaws, the drain gets a flood at once, and a partially blocked line can't keep up.

Turn cooling off. Find the condensate drain line where it exits outside, usually a white PVC pipe near the foundation or under an eave. Fit a wet/dry vacuum over the end and run it for two to three minutes. A clog often comes out as a slug of gray sludge.

In the attic, look for a capped tee on the drain line near the air handler. Pouring a cup of white vinegar down it monthly during summer keeps algae from rebuilding. Skip bleach; it corrodes some fittings.

If the float switch tripped and shut the system down, clearing the line and letting the pan drain will usually restore power. If the coil was frozen, let it thaw fully before restarting.

Call a pro if water keeps appearing after you've cleared the line, if the drain pan is rusted or cracked, if the leak is coming from the coil housing rather than the pan, or if there's any ceiling staining. Water damage in a hot attic escalates fast.

A tech will flush the line with pressure or nitrogen, verify the drain slope, check the pan and float switch, and confirm the coil isn't freezing. It's typically a same-day, under-an-hour repair.

LocalFixQuotes connects you with TDLR-licensed local HVAC contractors who handle drain problems every summer. We're a free matching service, not the contractor.