A few drops of water near your AC's indoor unit is normal — it's condensation from the cooling process. But if water is dripping steadily, forming a puddle, or staining your wall, there's a problem that needs fixing. Left unattended, AC water leakage causes wall damage, mould growth, and can short-circuit electrical components.
1. Blocked Condensate Drain Pipe
This is the most common cause — responsible for roughly 70% of AC water leakage complaints in Chennai. The indoor unit collects moisture from the air as it cools. This water drains out through a PVC pipe (the condensate drain). When this pipe gets blocked by algae, dust, or insects, water backs up and overflows from the unit.
Signs: Steady dripping directly below the indoor unit. Often smells musty because standing water grows algae.
Fix: A technician flushes the drain pipe with pressurised water or a wet-dry vacuum. This is a quick fix — under 30 minutes. To prevent recurrence, ask for a drain cleaning tablet to be placed in the drain tray during every service.
2. Dirty or Frozen Evaporator Coils
When the evaporator coils freeze over (due to a dirty filter or low refrigerant), they collect a thick layer of ice. When the AC turns off or switches to fan mode, this ice melts rapidly — producing more water than the drain tray can handle, causing overflow and dripping.
Signs: Water leaks mostly after the AC has been running for a few hours. You may see frost on the indoor unit or the copper pipes.
Fix: Switch the AC to fan-only mode for 2–3 hours to defrost. Then clean the filter. If the coils freeze again, the root cause (dirty coils or low gas) needs to be addressed by a technician.
3. Improper Installation or Tilted Unit
The indoor unit must be installed with a very slight tilt towards the drain side so water flows naturally into the drain tray and out. If the unit was installed level or tilting the wrong way, water pools on the wrong side and drips out of the unit casing.
Signs: Water drips from one end of the indoor unit, not from the centre or drain pipe end.
Fix: The mounting brackets are adjusted to correct the tilt. This is a 20-minute job and permanently fixes the issue.
4. Cracked or Overflowing Drain Tray
The plastic drain tray that sits below the evaporator coils can crack over time — especially in older ACs. A cracked tray cannot hold water long enough for it to drain, causing leakage through the bottom of the unit.
Signs: Water drips from directly beneath the indoor unit even when the drain pipe is clear.
Fix: The drain tray is replaced. It's an inexpensive part and straightforward to swap.
5. Low Refrigerant Causing Ice Buildup
When gas level is low, the evaporator coils run at abnormally low temperatures and ice forms on them. This is the same issue as #2, but caused by a gas leak rather than a dirty filter. The ice melts and overwhelms the drain system.
Signs: The AC cools poorly in addition to leaking water. Ice may be visible on the copper pipes outside the unit.
Fix: The gas leak must be found and sealed, then the system recharged. Simply adding gas without fixing the leak is a temporary fix.
What to Do Right Now
- Place a towel under the dripping unit to prevent floor or furniture damage
- Switch the AC to fan mode — this lets the coils defrost if they're frozen
- Check if the filter is dirty and clean it
- Call a technician if dripping continues after 2–3 hours in fan mode
RK Aircon technicians fix AC water leakage across all Chennai neighbourhoods. Most drain pipe blockage issues are resolved in a single visit, often within an hour.