Water Around Your Air Handler: Why the Drain Line Clogs Every Summer and What to Do

You walk into the garage or the hall closet and the floor is wet around the indoor unit. Or a brown stain is spreading on the ceiling below the attic. In our experience, a clogged condensate drain line is behind most of these calls. It's a simple problem, but ignoring it can turn it into an expensive one.

Where all that water comes from

An air conditioner doesn't only cool the air. It also pulls moisture out of it, and in our climate that's a lot of water. The cold indoor coil collects the moisture, which drips into a pan and then flows out through a drain line, usually a white PVC pipe that runs outside or to a drain.

Run the system most of the year in a humid place and that line carries water almost every day. Warm, wet and dark is exactly where algae and slime like to grow. Over time the buildup narrows the pipe until it blocks completely.

What happens when it clogs

With nowhere to go, the water backs up into the drain pan. A full pan overflows onto the floor, into the ceiling, or down into the insulation and drywall under an attic unit. Many systems have a float switch that shuts the system off when the pan fills. That's a good thing, but it also means you'll suddenly have no cooling and no obvious reason why.

If your system has no safety switch, or the switch fails, the water simply keeps coming. That's how a small clog becomes a ruined ceiling.

What to do right now

• Turn the system off at the thermostat so it stops making more water
• If water is near any electrical parts or the unit's wiring, shut off the breaker for the air handler too
• Soak up standing water with towels or a wet vacuum so it doesn't reach flooring or drywall
• Look at the drain pan. If it's full, that confirms the line is blocked
• Do not keep running the system to see if it clears itself. It won't

What homeowners can try

Some people pour a cup of white vinegar into the access opening on the drain line, which can break up light slime. Others use a wet vacuum on the outdoor end of the line to pull the clog out. Both are common steps, and both are fine to try if you're comfortable doing it and the power to the unit is off.

Neither one is a permanent fix, though. If the line has been slowly filling for months, you'll often be back in the same spot in a few weeks. And if the clog is deeper in the line, or the pan itself has been leaking, a household shop vac won't reach it.

When it's time to call

• The water comes back after you clear it
• The float switch keeps shutting the system off
• You can see a water stain on a ceiling or wall
• There's ice on the refrigerant line or the coil, which can mean a different problem is mixed in
• Water is pouring out of the air handler. That counts as an emergency, and you should call right away

Water pooling can also come from other places: a cracked pan, a rusted-out unit, or a coil that's freezing and then thawing. That's one reason we test instead of guess. When we come out, we trace where the water is coming from, clear the line, treat it so it stays clear longer, and show you what we found.

How to stop it coming back

Prevention is boring but it works. Drain lines should be cleared and treated at least once a year in our climate. That's built into every visit we do for Maintenance Club members: two visits a year, one before cooling season and one after, with the drain line cleared and treated each time. It's also part of our $69 new-customer A/C tune-up.

A change as simple as that costs a fraction of what a flooded ceiling does. Changing your filter on schedule helps too, since a dirty filter lets dust and debris reach the wet coil, and that debris feeds the slime in the drain line.

What we do when you call

We give you a real window, not sometime Tuesday, and a text when the tech is on the way. We find the cause, show you the clog or the failed part, and give you a flat price you approve before we start. The diagnostic fee comes off the repair if you go ahead, and our labor carries a one-year written warranty.

Standing water at 2am is exactly what our 24/7 line is for. Call (772) 284-5774 and someone will answer.