A puddle under the indoor unit. Drips from a ceiling vent. Water in the wrong place is the repair question Perth homeowners ask us most, and the cause is usually simple.
Key Takeaways:
- Almost every leak is condensate backing up instead of draining outside.
- A blocked drain line or tray is the most common cause, and often a quick fix.
- Heating and cooling take about 40% of the average Australian home’s energy use (CHOICE).
- Ice, ceiling stains or water near electrics need a licensed technician. Switch the unit off first.
Where the Water Comes From
Your aircon makes water whenever it cools: warm air crosses a cold coil, moisture condenses into a drain tray and runs outside through a drain line. A leak almost always means that water can’t get away.
Dust and mould slowly clog the tray and line until water backs up and drips into the room. Our guide to what an air conditioner service includes covers clearing them. Match the symptom to the likely cause:
| Symptom | Likely Cause | What to Do |
| Dripping from the indoor unit | Blocked drain tray or line | Turn cooling off, book a service |
| Ice on the pipes or coil | Dirty filter or low refrigerant | Clean filter; if ice returns, call a tech |
| Ceiling stain under ducted | Drain fault in the roof space | Switch off and call promptly |
| Outdoor unit dripping in winter | Normal defrost run-off | No action needed |
| Musty smell and damp | Mould in the tray or ducts | Book a clean and service |
The Checks You Can Do Yourself
Switch cooling off as soon as you spot water, then run two quick checks; ten minutes solves a surprising share of leaks.
Clean the return air filter if it’s grey with dust; choked airflow freezes the coil, and that ice melts as a leak. Then check the drain outlet outside: a steady drip while cooling is healthy, but bone dry on a muggy day points to a blockage, and it’s one of the classic signs your air conditioner needs a professional service. See how often your system should be serviced.
When It Needs a Licensed Technician
Call a professional when a leak keeps returning, ice rebuilds after a filter clean, water sits near wiring, or a ceiling stain is spreading. These are drainage or refrigerant faults you can’t reach from a stepladder.
Low refrigerant is a common cause of a frozen, leaking coil, and working on it legally requires an ARC refrigerant handling licence. WestOz Trades holds licence AU45143 and runs air conditioning repairs across Perth. Heating trouble instead this winter? Start with our aircon not heating guide.
Frequently Asked Questions
Condensate that should drain outside is backing up, usually because the drain line or tray is blocked with dust or mould. A filter clean and drain flush during a routine service fixes most indoor leaks.
Switch cooling off until the leak is sorted; running it risks ceiling damage, mould and water near electrics. Fan-only mode is safe, since the unit only makes condensate while cooling.
Usually that’s normal. In heat mode the outdoor unit ices up and runs a defrost cycle, shedding melted ice as water. Steady dripping indoors in winter is different and worth a professional look.
Water Where It Shouldn’t Be? We’ll Find It
Book a repair with WestOz Trades and a licensed technician will trace the leak and fix it properly. Get in touch today.
