Water dripping from your split system is one of the most common air conditioning complaints — and one of the most preventable. Here's what's causing it and what to do.
How Your Split System Drains Water (Normal Operation) When your split system cools the air, it removes moisture from it. This condensation drips into a drain tray inside the indoor unit, then flows through a drain pipe to the outside. Under normal operation, you'll see water dripping from the outdoor drain pipe — that's completely normal.
When water appears from the indoor unit, something in this drainage process has failed.
Cause 1: Blocked Drain Line (Most Common) The drain pipe from your indoor unit runs outside your home, usually through a small hole in the wall. Over time, algae, mould, dust, and debris build up inside this pipe and block it. When the drain blocks, water backs up and overflows from the indoor unit.
Fix: A technician clears and flushes the drain line. This is quick and inexpensive. Many homeowners in the Blue Mountains have this issue more frequently due to higher humidity — an annual service prevents it.
Cause 2: Dirty Evaporator Coil If the indoor coil is heavily caked with dust, it restricts airflow and causes the coil to freeze. When the system cycles off, the ice melts and the drain tray is overwhelmed.
Fix: A professional coil clean resolves this. The coil should be cleaned annually — more frequently in dusty or high-use environments.
Cause 3: Low Refrigerant Low refrigerant causes the coil to run too cold, leading to ice formation. When the ice melts, it overflows the drain tray. Low refrigerant almost always indicates a leak — simply topping up gas without finding and fixing the leak is a short-term solution.
Fix: A licensed technician must locate and repair the refrigerant leak before recharging the system.
Cause 4: Damaged or Misaligned Drain Tray Drain trays can crack or shift over time, especially in older systems. If the tray doesn't sit correctly under the coil, water misses the tray entirely.
Fix: Tray replacement or realignment by a technician.
Cause 5: Improper Installation If your unit was installed without the correct tilt, water can pool instead of draining. This is more common with discount installations.
Fix: The indoor unit needs to be repositioned.
What to Do Right Now If water is actively dripping from your indoor unit: 1. Place a towel or bucket under the unit to protect your floor or ceiling 2. Turn the unit off 3. Call a technician — most leaks are quick fixes when caught early, but water damage to ceilings and walls can be expensive if left unchecked
Betar Air services all split system brands across the Blue Mountains and Western Sydney. Call 0438 944 224 for a fast, professional service.