You noticed a water stain on the ceiling. Or maybe an actual drip. It’s coming from the area around your air handler — the indoor part of your AC system, usually in the attic or a utility closet. This is one of the most common calls we get in Houston.
Here’s what’s going on and what you need to do.
Your air handler produces condensate — water pulled from the air as part of the cooling process. In Houston’s humidity, a properly functioning AC system pulls 15–30 gallons of water out of the air per day. That water drains through a condensate drain line to the exterior.
When the drain line clogs — which happens regularly here because humidity and biological growth love a dark, moist pipe — the condensate pan overflows. The pan has a float switch designed to shut the system off before it overflows, but float switches fail. When the pan overflows, that water goes somewhere — usually down into your ceiling and walls.
If you just noticed a new stain and the ceiling feels dry to the touch: you may have caught it early. Get the HVAC company out to clear the drain line and check the float switch. Then monitor for two weeks.
If the stain is large, the drywall feels soft or spongy, the ceiling is sagging, or you smell something musty in that area: you have water inside the ceiling assembly — likely soaking the insulation, the back of the drywall, and possibly the ceiling joists. This needs a moisture assessment, not just an HVAC service call.
If the stain has been there for weeks and you’ve been meaning to deal with it: you probably have mold growing inside the ceiling. In Houston, active mold can establish in wet building materials within 24–48 hours. A stain that’s weeks old in an attic installation has been in mold-favorable conditions for most of that time.
If your system is still running and the drain is clogged, every hour it runs adds more water to the pan and potentially more overflow. Turn the system off until the HVAC technician clears the line.
Yes, it’s Houston, and yes, it will be uncomfortable. It’s better than a bigger water damage claim.
You need two different professionals here. An HVAC company fixes the condensate drain and float switch — that’s the source of the problem. A water damage restoration company assesses and dries what’s already wet — that’s the consequence of the problem. These are different scopes of work.
Don’t expect your HVAC technician to tell you whether you have water damage or mold in the ceiling. That’s not their assessment. And don’t expect a restoration company to fix your drain line. Get both calls made.
Sometimes, but it’s inconsistent. Some Texas insurers treat condensate overflow as a sudden, accidental event and cover the resulting water damage. Others treat it as a maintenance issue — a clogged drain line that should have been serviced — and deny the claim.
Whether you have float switch failure documentation helps. If the float switch malfunctioned (failed to shut the system off as designed), the argument for sudden and accidental is stronger. If the drain line was simply clogged from lack of maintenance, the insurer has a better argument for denial.
File the claim and let the adjuster make the determination. Don’t assume it’s not covered without asking.
Houston HVAC systems run 9–10 months of the year and cycle through massive amounts of humid air. The condensate environment inside an air handler and its drain system is inherently moist. HVAC mold in Houston is not rare — it’s a documented, recurring problem in homes across Katy, Sugar Land, Pearland, and the Heights, particularly in systems that aren’t serviced annually.
If your AC has been blowing air that smells musty, that’s a sign mold is growing inside the unit or on the evaporator coil — separate from the ceiling water damage issue but related to the same moisture problem.
Turn off the AC. Call your HVAC company to fix the source. Get a moisture assessment on the ceiling to find out what’s actually wet. If there’s been water in that ceiling for more than a day or two in a Houston summer, assume mold conditions are developing until you can prove otherwise.
If you have water stains and need a moisture assessment before deciding what to do next, call 247 Restoration Specialists. We’ll measure what’s wet, tell you whether professional drying is warranted, and help document for your insurance claim.
HVAC technicians in Houston typically recommend flushing condensate drain lines every 6 months — spring and fall — because the combination of high humidity and year-round system operation creates ideal conditions for biological growth inside drain lines. Many Houston homeowners do this themselves with diluted bleach or vinegar on a seasonal schedule.
A float switch is a safety device installed in the condensate pan that shuts the AC system off when the water level rises above normal — indicating a clogged drain. When float switches work, they prevent overflow. When they fail (which happens), the system continues running and the pan overflows into the ceiling. Float switch inspection is part of routine AC maintenance.
Not without first confirming the materials above the stain are actually dry. Painting over a water stain when the drywall and insulation above are still wet traps moisture and guarantees mold growth inside the ceiling assembly. Measure the moisture content first — if readings are elevated, dry before you repair.
