Homeowner answer
Why is water leaking from my AC indoor unit?
Water leaking from an AC indoor unit usually means condensate is not draining, most often because the drain line is clogged with algae or debris, the drain pan is cracked or rusted, or a frozen coil is thawing. Switch cooling off to limit damage, check the filter and drain, and book service.
Call soon
Water can damage ceilings, floors and drywall and lead to mold, so switch cooling off and book soon. If water is reaching outlets, light fixtures or electrical equipment, switch off that circuit at the breaker and keep clear.
Updated
The water is condensate — moisture your AC pulled out of the air — and it belongs in the drain line, not in your house. The first move is to stop making more of it; then find where it is going.
What you can safely check
- Switch cooling off
Do this:Set the thermostat to Off so the coil stops making condensate. Move belongings out of the way and put towels or a shallow container under the drip.
You should see:The drip should slow within a few minutes and stop as the system settles.
When to stop:Stop and keep clear if water is at, or running toward, outlets, light fixtures or anything electrical — that is a call-a-pro situation, not a cleanup.
- Look at the pan and the safety switch
Do this:Look at the pan under the indoor unit and at the float switch on the drain line, if there is one. Eyes only.
You should see:A dry or nearly dry pan. A little water at the very end of an extremely humid day can be normal; a full pan is not.
When to stop:Stop if the pan is full or the switch is sitting in water — the drain line is clogged and needs clearing by a technician.
- Check the filter while things dry
Do this:Hold the filter up to a light and replace it with the same size if no light comes through.
You should see:Light through the pleats, and the filter back in its slot with the airflow arrow pointing the same way. Good airflow keeps the coil from freezing, and melting ice is a common way pans overflow.
When to stop:Stop and leave cooling off if you see ice on the lines or the coil — let it thaw with the fan on and towels down, and do not run cooling until it has fully melted.
- Follow the drain outside
Do this:Follow the plastic drain pipe to where it ends outdoors, usually near the outdoor unit or the foundation wall.
You should see:An open end, clear of mulch, soil and plants. On a humid day with the AC running, the ground under it should be damp.
When to stop:Stop at the pipe's end — do not blow into the line or pour chemicals down it. If the outlet is buried or blocked, the clog is usually further up the line anyway.
Likely causes
- Clogged condensate drain line
Algae, slime and debris build up in warm, wet drain lines, especially in Florida. Water backs up and overflows the pan.
Handled by a technician
- Frozen coil thawing
When airflow is restricted or refrigerant is low, the coil ices up. As it melts, more water arrives than the pan and drain can handle.
Handled by a technician
- Dirty air filter
A clogged filter is a common reason the coil freezes in the first place.
Handled by you
- Cracked or rusted drain pan
Older metal pans corrode, and plastic pans can crack, letting water out even when the drain is clear.
Handled by a technician
- Disconnected drain pipe or failed condensate pump
Some homes use a small pump to lift water to a drain. If it fails or a pipe fitting comes apart, water spills out.
Handled by a technician
Call a pro when…
Book service as soon as you find water that is not from an obvious one-off spill, and before running cooling again if the drain pan is full.
- Water is dripping through a ceiling, a vent or a light fixture — keep the system off and keep clear of wet electrical.
- Water is reaching outlets, the electrical panel or anything plugged in.
- The pan fills again within days of being dried out — the clog will come back until the line is properly cleared.
- You find ice on the lines or the coil, or the leak started while the system was freezing and thawing.
- A musty smell lingers after everything has dried — the coil, pan or ducts may need cleaning.
Next step
Book a diagnosis
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Common questions
Is it normal for my AC to produce water?
Yes. An AC pulls moisture out of the air, and in Florida it produces a lot of water on humid days. That water should flow through the drain line to the outside or to a plumbing drain, not into the house.
Why does my AC leak only some of the time?
An on-and-off leak often means the drain is partly blocked and overflows only on the most humid days, or the coil is freezing and thawing. Both are worth fixing before the leak becomes constant.
Why did my AC shut off when it started leaking?
Your system probably has a float switch that turns the AC off when water backs up. It is preventing an overflow, and the drain needs to be cleared before the system will cool again.