The AC Was Cool. The Closet Was Dripping

As an Amazon Associate I earn from qualifying purchases. Some links are affiliate links.

The thermostat said 74. The closet ceiling had a brown ring. The air handler was doing its job. The PVC was not.

This is the Florida plumbing pattern people bring to a humidity site. They buy another portable unit. They turn the set point down. The pan keeps filling because the condensate line is a science experiment.

The AC is a water machine

A Florida coil pulls a lot of water out of the air. That water has to leave through a trap and a slope of white PVC, or a pump if the air handler sits in a closet or attic. Algae and slime love that trap. When it clogs, the pan is the only remaining drain. Then the pan overflows. Then the drywall reads wet and the hallway smells like a closed house.

The thermostat still says cool. Cool is not dry.

If the wall is already stained, pin it: moisture meter after a leak. Reed covers the relative humidity (RH) side: Florida humidity home guide. This note is the pipe.

What to look at before you buy capacity

1. The primary drain. Follow the PVC from the air handler. If you can see a trap, look for standing slime or a line that no longer slopes downhill.
2. The overflow pan. Standing water in the pan is a clog, not a dehumidifier problem.
3. The float switch. Many Florida installs have a wet switch that kills the compressor when the pan rises. If the house is hot and the pan is wet, that switch may have done its job. Do not jump it.
4. The secondary / pump. Closet and attic units often dump to a pump. A silent pump is not always a working pump. Look for a full reservoir and a dead outlet.

Do not open a pressurized supply. Do not cut copper. Condensate is gravity water until a pump is involved.

Flush what you can see

If the trap is reachable:

1. Turn the air handler off at the thermostat or breaker.
2. Open the cleanout if there is one. Many Florida traps have a T with a cap.
3. Flush with warm water. A cup of distilled vinegar in the trap helps slime. Do not pour drain crystals or tablet “pan bombs” into a line you cannot see the far end of.
4. Confirm water leaves at the termination — usually a splash block outside, sometimes a laundry standpipe.
5. Empty the pan. Restore power. Watch one cooling cycle.

If you cannot see the trap, the line is in a wall, the pan is rusted through, or water is in a ceiling, stop. That is a licensed plumber or HVAC tech, not a blog flush.

A wet/dry vac on the outdoor termination will pull a clog on many slab houses. Wear eye protection. Do not suck on a line that might be tied into a sewer.

What not to do

• Do not keep running the system “to dry the house” while the pan is overflowing. You are making more condensate into a failed drain.
• Do not jump the float switch so the AC will come back on. You will finish the ceiling.
• Do not treat a dripping closet as a reason to upsize a portable dehumidifier. Fix the line. Then measure relative humidity (RH).
• Do not pour bleach down a condensate line as a weekly lifestyle. It eats metal pans and does not replace slope.

Run this

1. Look in the pan today. Water there is the whole diagnosis.
2. Flush or vacuum the PVC you can see. If you cannot see it, call a licensed plumber or HVAC tech.
3. After the pan stays dry through a hot afternoon, log indoor relative humidity (RH) for a week. Hygrometer guide. If the room still sits above 60%, then size a machine: pint chart.

Carlo DeLuca is a third-generation master plumber. Family trade from Long Island, writing from coastal Florida. This note is not a service call. If the line is in a wall or the pan is gone, get a licensed plumber on site.

If it’s useful, it’s beautiful.