Why Is My Aircon Leaking Water Inside?
Indoor dripping usually means one of three things: the drain is blocked, the coil is freezing and thawing, or condensation is traveling the wrong path. The leak pattern tells you which.
1. Drain-Path Blockage
How This Works
If cooling still feels mostly normal but water drips steadily from one fixed point, the drain path is usually backing up. Dust, slime, and mineral residue collect in the tray or pipe until water queues inside the unit and spills over the tray lip instead of leaving through the drain as intended. If you are not sure whether the water points to drainage, icing, buildup, or trunking, use the aircon water leak checker before choosing the service.
How To Tell
A blocked drain causes a steady leak during the run cycle. The tray fills, water backs up, and it drips from the same spot each time. That differs from freeze-thaw, which gives sudden heavy bursts after shutdown, and from slope or routing faults, where the drip point can shift along the trunking. If cooling is still acceptable and the leak is constant, start with the drain path.
- Steady drip pattern during runtime.
- Gurgling water sound near the indoor unit.
- Cooling can still feel acceptable at first.
- Drip always from the same fixed point on the casing.
How We'd Confirm It
We clear and flush the drainage path, correct slope or insulation issues where needed, and retest under cooling load to confirm leaking stops.
Gas work will not solve a pure drain obstruction pattern. Confirm drain behavior before approving unrelated scope.
2. Freeze-Thaw Cycle
How This Works
If the leak comes in bursts after weaker cooling or after shutdown, the coil is usually freezing during the run and dumping meltwater when the ice releases. Low airflow or low refrigerant can push the coil below freezing. What looks like a drain problem from the room is often a freeze-thaw cycle instead.
How To Tell
The freeze-thaw pattern produces water in sudden, heavy bursts. It often appears after the unit shuts down, or after a period of noticeably weaker cooling. That differs from the steady drip of a drain blockage. With slope or routing faults, moisture appears in varying locations along the trunking. A freeze-thaw event floods the drain tray at once from a melting coil. If you see a large volume of water suddenly appearing, cooling that weakened before the leak worsened, or any signs of icing on the pipe, freeze-up is the suspect. Not a blocked drain.
- Leak appears in bursts, not a constant flow.
- Cooling weakens before leakage worsens.
- Icing signs may appear near the indoor area.
How We'd Confirm It
We remove the root restriction causing freeze-up, restore airflow or refrigerant balance as needed, and retest for stable operation without icing.
Treating every leak as a simple drain issue can miss the freeze trigger and lead to repeat leakage.
3. Condensation Routing Or Slope Issue
How This Works
If moisture shows up at different points along the trunking or wall, the issue is usually slope, routing, or insulation rather than a simple tray blockage. Water pools in a dip or forms condensation on an exposed cold section. The leak point then shifts instead of staying fixed.
How To Tell
The defining indicator of a slope or routing fault is that the drip point moves. Moisture appears at different positions along the trunking or wall lining over time, rather than consistently at one fixed spot as in a blocked drain. Unlike the freeze-thaw path where the failure is thermal and appears in bursts, this path is geometric: water follows the lowest available route through poorly sloped piping. If the drip location varies between rain events, runtime periods, or operating modes, trace the geometry of the drain installation before flushing the line.
- Drip location shifts along trunking or wall path.
- Leak timing changes with weather or runtime.
- Moisture appears even when cooling output seems normal.
How We'd Confirm It
We clear and flush the drainage path, correct slope or insulation issues where needed, and retest under cooling load to confirm leaking stops.
Replacing major components without confirming water-path behavior can add cost without solving recurrence.
Useful Next Steps
Related Reading
Ready to Get Started?
Tell us what’s going on. Symptoms, setup, photos, anything we should know. We’ll assess and come back with the right next step.