Air conditioning fails in February. Never in September, when someone could look at it calmly and order a part. Always on the third consecutive day over 38, when every technician in Melbourne is already booked.
That timing isn’t bad luck. It’s the system finally being asked to do what it’s been quietly failing at for months.
Here’s what actually goes wrong, and the small amount of maintenance that prevents most of it.
The five things that cause most failures
1. Blocked filters and coils
The most common cause by a distance, and the most preventable.
A clogged filter restricts airflow. Restricted airflow means the system works harder for less output, runs longer, draws more current and — in the worst case — freezes the evaporator coil or trips on thermal overload.
The tell: reduced airflow from the vents, the unit running constantly without reaching temperature, or ice on the indoor coil.
The fix: clean the filters. Genuinely, that’s it, and you can do it yourself in ten minutes. Monthly through summer, and once before the season starts. Outdoor condenser coils need clearing too — leaves, grass clippings and the general debris of a Melbourne garden.
2. Low refrigerant
Refrigerant isn’t consumed. If the level is low, there’s a leak, and topping it up without finding the leak is throwing money at a symptom.
The tell: the unit runs but doesn’t cool, ice forms on the pipework at the outdoor unit, or you hear a hissing or bubbling sound.
The fix: a licensed technician finds and repairs the leak, then recharges. Running a system low on refrigerant will eventually destroy the compressor, which is the single most expensive component.
3. Electrical faults
This is our part of the job, and it’s more often the culprit than people assume.
Failed capacitors are the classic — the unit hums but the fan or compressor won’t start. Contactors burn out. Loose connections at the isolator or in the outdoor unit heat up and eventually fail. Circuit breakers trip because the system is drawing more than it should.
The tell: the unit won’t start, trips the breaker, starts and immediately stops, or you can hear a hum with nothing turning.
The fix: electrical diagnosis. If your air conditioner is repeatedly tripping a breaker, don’t keep resetting it — that’s the system telling you something is drawing current it shouldn’t. See our fault finding service.
4. Drainage problems
Air conditioners produce condensate. It has to go somewhere.
A blocked drain line means water backs up into the tray and then into your ceiling. We’ve seen the aftermath of this in plenty of Melbourne homes, and the water damage costs several times what the drain clear would have.
The tell: water staining on the ceiling near the indoor unit, water dripping from the unit, or a musty smell when it runs.
The fix: clearing the line, and checking the fall on it. This is standard on an annual service and it’s the single best reason to have one.
5. Age and neglect
Systems have a service life — broadly 10 to 15 years for a split system, sometimes longer if it’s been looked after. Beyond that, efficiency drops, parts get harder to source, and you reach the point where a repair costs a meaningful fraction of a replacement.
The honest test: if the repair is more than about half the cost of a new system and the unit is over ten years old, replace it. A modern inverter system will use dramatically less electricity than a fifteen-year-old fixed-speed unit, and that difference shows up on every bill.
Evaporative cooling: different system, different problems
Plenty of Melbourne homes run evaporative cooling rather than refrigerated air conditioning, and it fails in its own particular ways.
Scale and mineral build-up on the pads. Melbourne water leaves deposits. Scaled pads mean poor cooling and restricted airflow.
Water pump failure. The pump circulates water over the pads. When it goes, you have a very large fan.
Float valve and water distribution faults. Either no water reaching the pads or water overflowing.
Belt and bearing wear on older units — usually announced by a squeal or a rumble.
Blocked or corroded water lines, particularly after a winter sitting idle.
The good news is that evaporative systems are mechanically simpler and generally cheaper to repair. The important thing is the pre-season service: evaporative units sit dry for six months and then get asked to run flat out. Most failures happen in the first fortnight of use, and almost all of them are preventable with a service in October.
What an annual service actually covers
Worth knowing so you can tell whether you’re getting one.
Filter clean or replacement. Indoor and outdoor coil clean. Refrigerant pressure check. Drain line clear and flow check. Electrical connections checked and tightened. Capacitor and contactor condition. Thermostat calibration. Airflow measurement. And for evaporative, pad condition, pump operation, water distribution and belt tension.
Book it in spring, not summer. In January you’re competing with everyone whose system has already failed.
The things that make a system last
Clean the filters. Monthly in summer. It’s the highest-return five minutes in home maintenance.
Keep the outdoor unit clear. At least 300mm of space around it, and don’t box it in with decking or screening.
Don’t set it to 16 degrees. It doesn’t cool faster — it just runs longer and works harder. 24 in summer, 20 in winter is the efficient range.
Run a ceiling fan alongside it. Moving air feels cooler, so you can set the thermostat two or three degrees higher for the same comfort. Over a Melbourne summer that’s a meaningful saving.
Run it briefly in the off-season. Ten minutes a month keeps seals and components from seizing.
When to call us
Call for: no cooling or heating, tripping breakers, water leaking from the indoor unit, ice on the pipework, burning smells, loud new noises, or a unit that won’t start.
We also do split system installation — including sizing and siting, which matters more than the brand you choose.
Registered Master Electrician. Over 200 five-star Google reviews. Lifetime workmanship warranty. We work across Melbourne’s eastern suburbs from Hawthorn.
Get in touch — ideally in October rather than February.