Short answer
Turn the AC off to stop more water, put a bucket under the drip, and check the secondary drain pan. Most ceiling leaks under an attic air handler come from a clogged condensate drain, a cracked pan or a missing float switch.
Right now
Turn the system off at the thermostat. If the ceiling is sagging, poke a small hole in the lowest point over a bucket to drain it in a controlled way, and keep people away.
Why it happens
The AC removes a lot of water on humid monsoon days. Algae and scale clog the drain trap, the primary pan overflows, and a rusted or missing secondary pan lets it through.
The fix
A tech clears and flushes the line, checks the trap and pan, and installs or tests a float switch so it shuts off before overflowing next time. Drywall repair is a separate trade.
How to clear a minor clog yourself
If you can reach the condensate line safely, many systems have a cleanout tee near the air handler. With power off, a wet/dry vacuum on the outdoor end of the drain line can pull out a soft algae clog. Pouring a cup of plain water through the cleanout afterward confirms it drains freely.
- Turn the system off at the thermostat and the air handler switch first
- Don't use bleach on PVC solvent joints repeatedly; follow the equipment maker's guidance
- Call a tech if the line is hard to reach or the pan is rusted through
Signs the drain is about to clog
Catching a slow drain early prevents ceiling damage.
- Water standing in the secondary pan
- Musty smell near the indoor unit
- Gurgling from the drain line
- The AC shutting off on humid days (float switch tripping)
Document damage for insurance and repairs
Photograph the ceiling, the air handler pan and any wet insulation before cleanup. Keep the technician's invoice that names the cause. Wet drywall and insulation should be dried promptly to limit mold growth.
Questions
Will homeowners insurance cover AC water damage?+
Policies vary. Sudden water damage is sometimes covered while slow leaks or maintenance issues usually aren't. Take photos and check with your insurer.
Is water leaking from my AC dangerous?+
The water itself is condensate, but it can damage drywall, soak insulation, encourage mold, and reach light fixtures. Turn the system off and keep water away from electrical fixtures.
How often should the condensate drain be cleaned?+
Once a year during a tune-up is typical, more often in humid regions or if the line has clogged before.
What is a float switch?+
A small safety switch in the drain pan or line that shuts the AC off when water rises, before the pan overflows. Attic air handlers should have one.
Editorial note: this guide is general information for homeowners, not a diagnosis. Desertline Heating & Air is a referral service; a licensed contractor should inspect your equipment before repairs.