Water and electrical appliances are not a good combination. When your air conditioner Melton starts dripping or pooling water, it’s not something to monitor and see how it goes. It needs to be addressed, because the secondary damage to ceilings, walls, and the unit itself can add up quickly. Here’s what’s actually causing the leak, and what should happen next.
How Water Gets Involved in Your Air Conditioner
When warm, humid air passes over the cold evaporator coil inside your unit, moisture in the air condenses on the coil surface — the same way a cold glass beads up on a humid day. This condensation collects in a drip tray and exits through a condensate drain line. Under normal conditions, you’d never notice it.
Problems start when something disrupts this drainage path, when the coil produces more moisture than the drain can handle, or when something causes ice to form and then melt rapidly.
The Main Causes of an Air Conditioner Leak
Blocked Condensate Drain
This is the most common cause. Over time, algae, mould, dust, and debris build up in the condensate drain line, restricting or completely blocking flow. Water backs up into the drip tray, overflows, and ends up inside the unit, on the ceiling, or dripping through the indoor unit onto the floor below.
It’s a fixable problem. A technician can clear the drain with a flush or vacuum. The key is catching it before the overflowing water has time to cause mould growth in ceiling cavities or water damage to plasterwork.
Dirty or Frozen Evaporator Coil
A coil that’s caked in dust and grime reduces airflow across the coil surface. This causes the coil to get excessively cold and freeze over. When the system cycles off or the freeze becomes severe enough, the ice melts rapidly and produces far more water than the drip tray and drain can handle.
You might notice the leak is intermittent — worse after the system has been running a while, or you may see ice on the indoor unit itself. Both point to a coil issue.
Low Refrigerant
When refrigerant levels are low, the pressure in the evaporator coil drops and the coil temperature falls below normal. This causes the coil to freeze, which then melts and floods the drip tray. If you’re seeing a leak and your system is also underperforming on cooling, low refrigerant is a likely culprit.
Cracked or Damaged Drip Tray
The drip tray beneath the evaporator coil can crack over years of thermal cycling. When it cracks, water escapes before it reaches the drain. This is more common in older systems and requires the tray to be replaced.
Improper Installation
An indoor unit that isn’t perfectly level will drain poorly. If the unit is tilted even slightly in the wrong direction, water pools on one side of the tray and eventually overflows. This is an installation issue and is correctable, but it does require a technician to re-mount the unit correctly.
High Humidity Conditions
On extremely humid days, a system working at its limits can produce more condensation than usual. Combined with a partially blocked drain or a slightly compromised tray, this can tip the balance toward a visible leak. This is less common in Melbourne’s west than in coastal areas, but it does occur on storm-front days.
Conclusion
Turn the system off. Running a leaking unit risks water reaching the electrical components, which can cause shorts and more serious faults. Place a towel or container to catch any dripping water and protect your ceiling or flooring.
Call a technician. Diagnosing the exact cause requires inspecting the coil, drain, tray, and refrigerant levels. It’s not a DIY investigation.
New Image Heating and Cooling West Melbourne responds quickly to service calls. We’ll identify the source of the leak, fix it properly, and check that there’s no secondary damage requiring attention. Call 0468 125 098.
Frequently Asked Questions
Is it dangerous to run an air conditioner that’s leaking water?
Yes. Water near electrical components is a serious risk. Turn the unit off until a technician has assessed and repaired the cause of the leak.
How do I know if the condensate drain is blocked?
You may notice water overflowing from the indoor unit or dripping from a ceiling near the unit. If you can access the drain outlet outside, check whether water is draining properly when the system runs. If not, the drain is likely blocked.
Can I clear a blocked condensate drain myself?
Some homeowners use a wet vacuum to suction out a drain blockage. This can work on simple clogs but doesn’t address the underlying build-up of algae or mould. A professional flush clears it more thoroughly and treats the drain to prevent quick regrowth.
Why does my air conditioner only leak on very hot days?
On high-demand days, the system works harder and produces more condensation. A drain or tray that manages on mild days can overflow under heavy load. It’s an early warning sign that the drainage system needs attention.
Could a water leak from my air conditioner cause mould in my ceiling?
Yes. Water in a ceiling cavity creates ideal conditions for mould growth. If the leak has been ongoing for more than a short period, it’s worth having the ceiling cavity inspected along with the air conditioner repair.
