AC leaking water inside? Do this first.

Air conditioning removes humidity as well as heat. Warm indoor air passes over a cold coil, moisture condenses out of it exactly as it does on a cold drink, and that water drips into a pan and runs out through a drain line. On a humid day a system can produce several gallons. So water itself is normal — water in the wrong place is the fault.

1. A clogged condensate drain line — the overwhelming favourite. The drain is a narrow pipe, usually PVC, and it stays permanently damp, so algae and slime build up inside and eventually block it. The pan then overflows. Many systems have a float switch that detects the rising water and shuts the air conditioner off deliberately — so if your AC has stopped working AND there is water, this is very likely why. A wet/dry vacuum applied to the outdoor end of the drain line will often pull the clog straight out.

2. A frozen coil that has thawed. If the coil iced over — from a clogged filter or low refrigerant — it will dump far more water than the pan can handle once it melts, and overflow. The tell is a large volume of water arriving at once, often after the system has been switched off. Fix the underlying airflow or refrigerant problem, not just the water.

3. A rusted or cracked drain pan. On systems fifteen years and older, the pan itself corrodes through. Water then bypasses the drain entirely and lands wherever gravity takes it. A pan can be replaced, but on a unit that old it is worth weighing against replacement.

4. A disconnected or badly sloped drain line. The line relies on gravity. If it has been knocked, sagged, or was installed with insufficient fall, water backs up and spills. This shows up commonly after other work has been done near the unit.

5. Poor insulation on the refrigerant line. Sometimes what looks like a leak is condensation forming on a cold, bare copper line and dripping. Re-insulating the line solves it.

Why not to ignore it. The water itself is cheap; what it lands on is not. An attic unit dripping onto drywall causes ceiling damage and mould that costs far more than the repair. And if a float switch has shut your system down, it will stay off until the drain is cleared — that is the safety working correctly, not a second fault.