After "not cooling," a leaking AC is the summer call we run most in the Pearland-Houston corridor. The good news: the water is almost never a refrigerant problem or a broken part. It is drainage. The bad news: ignored drainage takes out ceilings, flooring, and attic insulation, and it does it fast in July when the system is producing its maximum condensate.
Where the water comes from
Your indoor coil does two jobs. It cools the air, and it wrings the moisture out of it. That moisture condenses on the cold coil, drips into a pan under it, and leaves through a PVC drain line, usually to a stub outside near the condenser. On a humid Houston day a residential system can pull 5 to 20 gallons out of the air. All of it has to pass through a drain line about as wide as your finger.
That line stays wet and dark all season, which makes it a perfect place for algae. The sludge builds until the line blocks, the pan overflows, and the water goes wherever gravity takes it: through the ceiling under an attic unit, across the closet floor around a vertical unit, or into the emergency pan if you have one.
The causes, in the order we find them
1. Clogged condensate drain line
The cause on most leaking-AC calls we run. Algae and dust sludge block the line right at peak condensate season. Fix: clear the line. You can often do this yourself with a wet/dry vacuum at the outside stub (steps below). If the clog is past the trap or keeps coming back, a professional drain line cleaning clears the full run and treats the line against regrowth. $150 to $250, flat-rate, in writing.
2. Frozen coil melting off
A dirty filter or low refrigerant can ice the coil solid. When the system cycles off, the ice melts faster than the pan and drain can handle, and it looks exactly like a drain leak. If you saw ice on the copper lines before the water showed up, treat it as a freezing problem. The water is the symptom, not the cause.
3. Rusted or cracked drain pan
Primary pans on systems past 12 to 15 years rust through, especially at the corners. Water appears under the unit even though the drain line runs clear. Fix: pan replacement. This one is not a DIY job; the pan sits under the coil and the coil has to come up to swap it.
4. Disconnected or unglued drain fitting
We find these on systems that were installed or serviced carelessly. A fitting that was never glued eventually works itself loose and drips inside the closet or attic. The giveaway is water at a joint in the PVC rather than at the pan.
5. Failed float switch that never tripped
The float switch is the little device that is supposed to shut the system down before the pan overflows. When one fails silently, the first sign of trouble skips straight to a ceiling stain. If your leak reached drywall without the system ever shutting itself off, have the switch checked during the repair. If your system has no float switch at all, add one; it is cheap insurance for any attic unit.
What not to do
- Do not keep running the system "to see if it stops." It will not. Runtime is water production.
- Do not pour bleach down the line as a fix for an active clog. It sits on top of the blockage without moving it, and strong bleach attacks the glue joints in older PVC. Clear the clog first; treatment comes after.
- Do not ignore water in the emergency pan because "the pan caught it." The emergency pan is the last line of defense, and pans rust. Treat water there as an active failure.
When it is a service call
Call us the same day if any of these is true: water reached a ceiling, a wall, or flooring; the emergency pan has standing water; the vacuum trick did not stop the leak; the leak comes back within a week; or the water showed up together with ice on the lines or warm air at the vents. That combination points past the drain to the repair side of things, and it is exactly what same-day slots are for. A recurring clog is also the sign of a line that needs a proper cleaning and treatment rather than another rescue with the shop vac. If you want the drain checked before it ever backs up, that is part of every tune-up we do.
Water in the pan and it's 98° outside? That's a same-day call: 281-992-7866 or book online. No overtime fees, ever. 2am costs the same as 2pm.