The short answer
Most indoor leaks come from a clogged condensate drain line. Your AC pulls gallons of water out of the air on a humid day, and algae and dust in the drain line eventually block it. Turn the system off, clear the drain, and dry the pan. If the pan is rusted through, the coil is frozen, or water is coming through a ceiling, call for service right away.
Where the water comes from
As humid air crosses the cold indoor coil, water condenses on it the same way it does on a glass of iced tea on the porch. That water drips into a pan and runs out through a PVC drain line, usually to the outside or into a plumbing drain. In a York County summer, that can be several gallons a day.
What you can check
- Turn the system off at the thermostat so it stops making more water.
- Look at the drain pan under the coil. Soak up standing water with towels or a wet/dry vacuum.
- Find the end of the drain line outside. If it isn't dripping while the system runs, the line is probably clogged.
- Clear it: vinegar or warm water poured into the cleanout, or a wet/dry vacuum on the outside end.
- Check for ice on the coil or lines. A thawing coil can dump more water than the pan can handle.
Attic units need extra care
Many newer homes around Fort Mill, Tega Cay and Indian Land have the air handler in the attic. Those systems should have a secondary pan with its own drain or a float switch. A stain on the ceiling below means water already got past both. Turn the system off and call.
When to call
- The pan won't drain after you clear the line.
- The pan is rusted or cracked.
- A condensate pump isn't running.
- Water is reaching wiring, an outlet, or the ceiling. Shut off the breaker first.
Call Thermal Services at (704) 701-6478. Drain cleaning is part of every good maintenance visit, and it's the cheapest way to avoid a ceiling repair.
Common questions
How do I clear an AC condensate drain line?
Many systems have a T-shaped vent with a cap on the drain line near the indoor unit. With the power off, remove the cap and pour in a cup of distilled white vinegar or warm water to break up buildup. A wet/dry vacuum on the outside end of the line can pull a clog free. If the pan still won't drain, call.
Why did my AC shut off and there's water in the pan?
Many systems have a float switch in the drain pan or on the drain line that turns the AC off when water backs up. It's a safety device doing its job. Clear the drain, let the pan empty, and the system should restart.
Can a furnace leak water?
A high-efficiency (90%+) gas furnace makes its own condensate, and its drain and pump can clog or fail. Water around a furnace in winter usually points to that drain, its condensate pump, or a split drain hose.