Getting your air conditioning ready for a heatwave

Summer in Melbourne's west doesn't warm up politely. The Bureau of Meteorology describes Melbourne as sitting between the hot, dry interior and the cold Southern Ocean, with warm northerly winds often arriving ahead of a cold front. On those days an air conditioner goes from barely used to flat out in one afternoon.

The really hot days are few but they bunch up. The Bureau's Laverton station, with records back to 1943, averages 27 days a year at or above 30 °C and 9.4 at or above 35 °C, mostly between December and February. Its January record of 45.6 °C was set on 27 January 2026.

Victorians typically use more energy for heating than cooling, the Victorian Government notes, so cooling mode can go most of a year without a real workout. A slow drain, a tired fan motor or a small leak stays hidden until the system is asked to work hard.

Victoria's Department of Health advises checking, before extreme heat, that your fan and air conditioner work well, and having the air conditioner serviced if needed. Do the first part on a warm but ordinary spring day, when a problem is an inconvenience rather than a crisis.

Switch each unit to Cool, not Auto or Dry, and set it a few degrees below room temperature so the compressor has to start. Give it a good half hour. The air should feel properly cold and steady, not just moving. Outside, the fan should be turning and the unit should sound even, with no grinding, rattling or repeated clicking.

On a ducted system, try each zone from the controller and walk every room. On a split system, check the small drain pipe outside after a while on cooling; it should drip. Nothing on a humid day, or water appearing inside, means the drain needs attention now, not in January.

Filters come first. The Victorian Government suggests cleaning the dust filters on a reverse-cycle unit about twice a year, more often with heavy use, following the manual. Dirty filters significantly reduce airflow and efficiency. A ducted system's filter sits in the return-air grille, often in a hallway ceiling, so only tackle it from a stable step.

Then give the outdoor unit room to breathe. It's where your house's heat ends up. Clear leaves and clippings, move the bins and the stack of pavers, and cut back shrubs to the clearances in the manual. Don't hose it, spray cleaner into it or throw a tarp over it for shade.

That's where homeowner maintenance stops. Energy Safe Victoria says electrical work isn't a DIY job, even small ones, so leave the isolator, covers and wiring alone. The Australian Refrigeration Council requires a Refrigerant Handling Licence for servicing that risks refrigerant escaping. Better Health's advice includes keeping evaporative pads clean, but on a roof-mounted cooler that's a service job, not a ladder job.

If the test run turned anything up, or nobody remembers the last service, book one before the season. Federal bench testing found common faults caused average energy losses of 14% to 20% across most tests, and where several faults co-existed, energy use rose substantially, with a high likelihood of failure if they were left.

On a split system, a proper service goes well past a filter wash: indoor coil, fan wheel and louvres cleaned, the drain flow-tested to its outlet, the outdoor coil cleared, and brackets, pipe insulation, isolator and cable entries checked before a run in cooling. Ducted systems add the return-air filter, zone motors and controller. Evaporative coolers need pads, water distribution, pump and drain checked.

What a service shouldn't include is a routine refrigerant top-up. Refrigerant runs in a sealed loop and isn't used up, so a low system has a leak. The Australian Refrigeration Council says topping up before a system is fully tested and every identified leak repaired is illegal.

Every air conditioner has a limit, and a run of extreme days finds it. Start cooling in the morning before the house soaks up heat, rather than dragging a baking house down late in the afternoon. Close blinds on the sunny side early and shut doors to empty rooms.

The Victorian Government suggests 24 °C to 26 °C for living areas when cooling, and says every degree lower adds around 10% to running costs. On ducted systems, use the zones; the Victorian Government recommends them so each area can be heated or cooled on its own.

Evaporative cooling is different. It needs some windows or doors open so hot air can escape, and it works well in low-humidity inland regions, which is why it struggles on sticky days. Shut every window and it has nowhere to push the hot air.

The Department of Health issues a heat health warning in response to a new Bureau severe or extreme heatwave warning. Hobsons Bay, Wyndham, Brimbank, Maribyrnong and Port Phillip are all in its Central district. Among those most at risk it lists people over 65, pregnant women, babies and young children, people with health problems and people with limited ways to keep cool.

If someone like that lives with you, decide now where you'd go if the cooling failed, and keep a fan you know works. The department's extreme heat advice is to use air conditioning or a fan.

If the unit stops, check the mode, set temperature, timer and remote first. If a safety switch has tripped, Energy Safe Victoria says to reset it and call a licensed electrician if it won't reset. Reset it once only. Ice on the pipes means switch off and let it thaw. A hot or burning smell means turn it off, switch its circuit off at the switchboard if that's safe, and if there's smoke or fire, get everyone out.

A cooling appliance or service provided by the rental provider that isn't working is on Consumer Affairs Victoria's list of urgent repairs. Rental providers must make urgent repairs immediately, and they pay unless the renter caused the problem.

Report it in writing to the agent or rental provider straight away, noting what the unit is doing, any error code and whether a safety switch tripped. For rental providers, a spring service saves everyone a miserable week.

Book a service if your test run showed weak or warm air, a drain that isn't running, new noises, an error code or a dead zone, or if the system is simply overdue. Spring is the easy time: there's room to order a part, and nobody is sweltering while they wait.

Get in touch sooner for anything electrical: a unit that trips its circuit, a scorched isolator, a burning smell or a controller that goes dead. We're one local team for electrical, heating and cooling, so one visit can look at both the circuit and the unit.

If the system is getting on, plan a replacement on your own terms rather than in a heatwave. The Victorian Government says a reverse-cycle system more than 15 years old typically uses more than three times the energy of a modern one, and it's worth checking whether your switchboard needs an upgrade for a new system. Either way, you get honest advice and the price before we start.