When is the best time of year to install air conditioning?

Summer in Melbourne's west arrives in bursts. Laverton averages 27 days a year at or above 30 °C and 9.4 days at or above 35 °C, mostly between December and February, and they often arrive on hot northerly winds. The first of those days is when systems that sat idle for months get switched on, and when the ones that won't start are found.

Winter does the same in reverse. July is Laverton's coldest month, with a mean minimum of 5.2 °C, and Victorians use more energy for heating than cooling. A reverse-cycle system that quits on the first cold night leaves the household without its main heating, right when every installer's phone is ringing.

With no deadline, you can get a proper look at the rooms, compare a like-for-like replacement with something better suited to how you now use the house, and choose a model by its capacity and Cold-zone heating rating rather than by what's in stock. If the switchboard needs work or a new circuit, there's time to do it properly.

The work itself is easier too. A ducted install means hours in the roof space, which on a summer afternoon can be far hotter than outside. In September or April it's comfortable enough to seal joints and insulate ducts carefully. Even a wall split goes in more smoothly when nobody is waiting on it to cool a baking house.

Spring installs can be tested on cooling before summer, and autumn installs on heating before winter. A drain that needs adjusting or a zone that needs balancing gets sorted while it's an inconvenience, not a crisis.

If your system is getting on, plan its replacement rather than letting it choose the date. The Victorian Government says a reverse-cycle system more than 15 years old will typically use more than three times the energy of a modern one, so an old unit that still runs may already be costing you more than you think.

None of the signs below mean a system must go tomorrow. Each is a reason to get a replacement scope ready in the shoulder season, so the decision is made on your timing.

Start with the simple checks: mode, set temperature, timer and remote batteries. 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, and leave the isolator and covers alone.

Then ask for a diagnosis before deciding anything. Many mid-season faults are repairable, and a repair can carry you through to spring or autumn, when a replacement can be planned properly. If the system can't be repaired, a like-for-like swap may be quickest, but check the old size actually suited the rooms before repeating it.

Meanwhile, keep the household safe. Victoria's health department advises using air conditioning or a fan in extreme heat, and people without a way to keep cool are among those most at risk. Keep a working fan, close the blinds on the sunny side, and if someone vulnerable lives with you, decide where they could go on the worst days.

For rental providers, the calendar matters even more. A cooling appliance you supplied that isn't working is on Consumer Affairs Victoria's urgent repairs list, as is a heating appliance that has stopped. Replacing a tired system during a vacancy or in the shoulder seasons avoids an urgent job in the worst week of the year.

From 1 March 2027, energy-efficient fixed cooling with an outlet in the main living area is required when a new rental agreement starts. Lining that work up with a spring or autumn vacancy is far easier than squeezing it in between tenants in January.