WHY IS MY AC LEAKING WATER INSIDE?
Deep summer is when this one starts showing up: a puddle around the furnace or air handler, a damp spot on the floor, or a brown stain spreading on the ceiling under an attic unit. It's alarming to find, but here's the reassuring part; most of the time it's a clogged drain, not a catastrophe, and often it's something you can sort out yourself. Here's why your AC is leaking, and what to do about it.
Why is my AC making water at all?
Your air conditioner doesn't just cool the air, it pulls moisture out of it. Even in our dry Treasure Valley climate, all day long that humidity condenses on the cold indoor coil, drips into a pan beneath it, and runs out through a drain line, usually to the outside of your house or a nearby floor drain.
So your AC is supposed to produce water. It's only a problem when that water can't get to where it's going, and that's what a leak actually is.
Why is it leaking instead of draining?
Nine times out of ten, the drain line is clogged. Over a summer of running, algae and gunk build up inside that line, water backs up in the pan, and once the pan is full it spills over onto your floor or through your ceiling.
The other usual suspects:
- A frozen coil that thawed. If your system iced up recently, usually from a dirty filter or low refrigerant, all that ice melts at once and dumps more water than the pan can handle. (If that rings a bell, our post on AC ice is the prequel to this one.)
- A cracked or rusted drain pan that's simply leaking through.
- A failed condensate pump. If your air handler is in a basement or somewhere the water has to be pumped up and out, a dead pump means it backs up instead of draining.
What should I do the moment I see water?
First, turn the system off. Running it just makes more water and more mess while you sort it out. Then mop up what's there so it doesn't soak into flooring or drywall.
Next, take a look at the unit. If you see standing water in the pan, the drain's your problem. Two things help:
- Change your filter. If a dirty filter freezes the coil, a fresh one keeps it from happening again once everything's dry.
- Clear the drain line. The most common DIY method is running a wet/dry vac on the outside end of the drain line to pull out the clog, or flushing the line with a little vinegar through the access port near the air handler to break up the gunk. If you've got pressurized air, that might do the trick too.
One more thing worth knowing: many systems have a small safety float switch that shuts the AC off when the pan fills up. So if your AC suddenly won't run and there's water sitting in the pan, that switch is probably doing its job. Clear the water and the clog, and it should kick back on.
Can I fix it myself, or do I need to call?
A simple drain clog and a filter change are fair game for most homeowners. If that clears it and it stays clear, you're done.
Call us if the line clogs again right after you've cleared it, if the leak is coming from a coil that keeps freezing (that usually means low refrigerant, which is licensed work), if your condensate pump has failed, or if the pan itself is cracked or rusted through. And definitely call if water has already reached your ceiling or drywall, at that point the leak is the smaller problem.
The short version
Water inside almost always means a clogged drain line or a thawed-out frozen coil. Shut the system off, dry up the water, change your filter, and clear the drain. If it keeps coming back, the cause is deeper and worth a look.
We're a family-run shop covering Nampa, Caldwell, Meridian, Boise, and beyond. 208-455-5158 if you need us.