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Air conditioner leaking water inside
An air conditioner pulls water out of the air all day. A leak indoors means that water has lost its way out.
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The short version
- Most likely cause
- A clogged condensate drain line.
- Safe to do
- Switch the system off and soak up the water.
- Call a technician when
- Water is near wiring, coming through a ceiling, or the leak returns.
Safe to do yourself
- Turn the system off at the thermostat.
- Soak up standing water to protect floors and ceilings.
- Check the filter and replace it if it is dirty.
- Look for a full drain pan under the indoor unit.
Stop and call
- Water is dripping through a ceiling.
- Water is near the furnace or electrical parts.
- The drain pan is rusted through.
- The leak comes back after the line was cleared.
Where the water goes wrong
- A clogged drain lineAlgae and dust build up in the drain line. Keeping the drain channels clear is part of routine maintenance.
- A cracked or rusted panThe pan under the indoor coil catches the water. Old metal pans rust through and plastic ones crack.
- A frozen coil thawingIce on the coil melts faster than the drain can carry it. The real problem is whatever caused the ice.
- A failed condensate pumpWhere the unit sits below the drain, a small pump lifts the water out. When it fails, the water backs up.
What a technician will do
- Find where the water is escaping.
- Clear the drain line and test that it flows.
- Inspect the pan, the pump and the safety switch.
- Check the coil for ice and the filter for dirt.
Water that has soaked a ceiling or wall for more than a day or two is also a moisture problem. It is worth having the area dried properly.
Related guides
Ice on the air conditioner
Air conditioner running but not cooling
Air conditioner making a loud noiseSources
- US Department of Energy