My air conditioner won't restart after a power outage. What now?

Air Conditioner Won't Restart After an Outage?

The short answer

Give it a few minutes first. Many units wait before restarting the compressor after power returns, and some need a press on the remote rather than starting on their own. Then check the switchboard for a tripped breaker or safety switch, and whether the wall controller or Wi-Fi app needs resetting. If it's still dead or shows a fault, the outage or a surge may have damaged the control board.

Restart delays and auto restart

After power returns, most air conditioners hold off restarting the compressor for a few minutes to protect it. Some models have an auto restart setting that picks up where they left off; others stay off until you turn them on again. Ducted wall controllers can lose their clock, schedules or zone settings and need setting up again, and Wi-Fi adapters can take a while to reconnect to the router.

Check the switchboard

When power comes back, everything that was left on starts at once, which can trip a breaker or safety switch. Check the switchboard and reset a tripped switch once. If it won't stay on, leave it off and call a licensed electrician. If the board is labelled and safe to reach, you can also switch the air conditioner's circuit breaker off for a couple of minutes and back on, which resets many units.

When the outage did damage

A surge, or a run of flickers as the power came and went, can damage the control board, a fuse on the board or the power supply in the outdoor unit. Signs include a dead display after the power is back, a new fault code or a burning smell. Leave the unit off and have it tested. A surge protection device at the switchboard captures voltage spikes from events such as lightning, though it doesn't protect people from electric shock.

Next time, Energy Safe Victoria's advice for a power failure is to turn off and unplug appliances at the power point to help prevent surge damage. An air conditioner can't be unplugged, but turning it off at the remote or controller until power has been steady for a few minutes helps.

What you can safely do now

Wait a few minutes after power returns, then turn the unit on with the remote.
Check the switchboard and reset a tripped breaker or safety switch once.
Reset the wall controller, or reconnect the Wi-Fi app, if its settings were lost.
If there's a burning smell or the display stays dead, leave the unit off and have it checked.
During a future outage, turn the air conditioner off until the power is steady again.

Services that can help

Split System RepairsWater leaks, error codes, weak cooling and systems that will not start.Breakdown Repairs & Fault FindingHeating and cooling faults found, explained and fixed properly.Surge ProtectionSurge diverters fitted at the switchboard to protect your appliances.

Sources for this answer

3 sources, with the date each was checked

1.Energy Safe Victoria: Locate your electricity box outside your home and check whether the safety switch has tripped. If it has tripped, reset the switch. If the switch won’t reset, call a licensed electrician. Accessed 30 September 2026.
2.Energy Safe Victoria: Surge diverters protect the property from voltage surges such as those resulting from a lightning strike. The surge diverter captures the voltage spikes in the wiring that would otherwise be transferred into the… Accessed 30 September 2026.
3.Energy Safe Victoria: In the event of a power failure turn off and unplug all electrical appliances at the powerpoint. This will help to prevent equipment damage in the event of a power surge. Accessed 30 September 2026.

General information for homes in Victoria. Every installation is different, so treat this as a starting point. Where this answer refers to Victorian safety or rental rules, the sources above have the current requirements.