An indoor aircon unit that drips water onto the floor — or worse, into the wall and ceiling — looks like a serious fault. Usually it isn't. Your aircon doesn't just cool the air; it pulls moisture out of Malaysia's humid air, and that water is meant to drain away through a small pipe. When the water ends up on your floor instead, it's almost always a drainage problem, not a broken unit.
Left alone, though, a leak can swell paint, rot plaster and damage anything below it — so it's worth sorting quickly.
The five real causes
- A blocked drain pipe (by far the most common). Dust, slime and even dead insects collect inside the condensate drain. Once it's blocked, the water has nowhere to go and overflows out of the indoor unit. This is the cause in the large majority of leaks we see.
- A dirty filter or frozen coil. A choked filter can make the coil ice over; when the ice melts, it produces more water than the tray can handle, and it spills.
- Low refrigerant. Low gas can also freeze the coil, with the same melt-and-overflow result. (Low gas means a leak somewhere — see our note below.)
- A cracked or rusted drain tray. On older units — typically 7+ years — the tray that catches the water can crack or corrode, letting water drip straight through. This one needs a technician.
- A bad installation. If the indoor unit was mounted tilted the wrong way, water runs toward the wrong side instead of into the drain. Common on units fitted in a hurry.
The 5-minute check you can do safely
First: switch the unit off at the wall. Never poke around a running unit. Then:
1. Find where the drain pipe exits — usually a thin pipe running outside the house or to a floor drain. 2. Check the outlet isn't submerged in a puddle, kinked, or blocked with leaves and gunk. 3. Clear anything obvious from the pipe opening. 4. Check (and rinse) the indoor filter while you're there. Many leaks clear up with nothing more than this.
When to call a professional
If the leak continues after you've cleared the drain outlet and cleaned the filter, the blockage is deeper inside, or the problem is a cracked tray, a frozen coil, or low gas. These aren't DIY jobs — they involve opening the unit, flushing the drain line under pressure, or finding a refrigerant leak. A proper service will clear the full drain path and check the tray and coil so the leak doesn't simply come back next week.
One thing to insist on: if a technician says the unit is “low on gas”, the gas leaked out somewhere. A blind top-up without finding that leak just pays to refill a system that will empty again. Find the leak first.
Common questions
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