Water on the floor around your indoor air handler is not normal. If you see it, turn the system off at the thermostat immediately. Running the AC while water is backing up risks ceiling damage, drywall damage, and mold growth inside the wall cavity.
Now figure out why.
Why your AC produces water in the first place
The evaporator coil inside your air handler cools the air passing over it. When warm, humid air hits the cold coil, moisture condenses on the surface — the same thing that happens on a cold glass on a summer day. That water drips into a drain pan below the coil and flows out through a PVC condensate drain line, usually to the outside of the house.
In a Florida summer, a properly working AC can pull 5 to 20 gallons of water out of the air per day. That is a lot of water moving through a small pipe. When the pipe clogs, the water has nowhere to go but into your house.
The most common cause: clogged drain line
This accounts for the majority of AC water leak calls in Florida. Algae, mold, and sludge grow inside the PVC drain line because it is constantly wet in a humid climate. Over time the buildup blocks the pipe.
Signs: Water pooling around the air handler. The system may shut itself off if a float switch is installed — the float rises with the water level and kills power to the system before the pan overflows. If your AC stopped running and there is water in the drain pan, this is almost certainly what happened.
What you can do: Locate the drain line cleanout — a capped T-fitting on the PVC pipe near the air handler. Remove the cap and pour a cup of distilled white vinegar through it. If the line is only partially blocked, this may clear it. If water is already overflowing, the blockage is past what vinegar can reach. You can try a wet/dry vacuum on the outdoor end of the drain line to pull the clog out. If neither works, a technician will use a nitrogen flush or a specialized pump to clear it.
Prevention: Pour a cup of vinegar down the cleanout once a month during the cooling season. This kills algae before it becomes a blockage.
Other causes
Dirty air filter. A clogged filter restricts airflow over the evaporator coil. The coil gets too cold, frost forms on it, and when the system cycles off, the frost melts faster than the drain pan can handle. Replace the filter and let the coil thaw before restarting.
Cracked or rusted drain pan. On systems older than 12 to 15 years, the drain pan beneath the coil can rust through or crack. Water drips straight through the pan instead of flowing to the drain line. The pan needs to be replaced — there is no reliable patch for a rusted pan.
Disconnected drain line. The PVC fitting where the drain line connects to the pan can come loose, especially after service work or if the line was not properly glued. Water drips from the gap. Check that the connection is tight and sealed.
Low refrigerant. Like a dirty filter, low refrigerant causes the evaporator coil to freeze. The ice melts and overwhelms the drain pan. If you hear a hissing or bubbling sound near the indoor unit, refrigerant may be leaking. This requires a technician.
What to do right now
- Turn the thermostat to "off."
- Mop up the standing water. If it has reached drywall or ceiling material, dry the area with fans immediately. Mold can begin growing within 24 to 48 hours in Florida humidity.
- Check the filter. Replace it if dirty.
- Try the vinegar flush or wet/dry vacuum on the drain line.
- If the water returns after restarting, call a technician.
Call (727) 477-3256 any time. Water damage gets worse every hour — if you are unsure, call first and troubleshoot second.