Why won't my air conditioner turn on?

Rule out controller issues first

Replace the remote batteries and make sure the controller is addressing the correct indoor unit. Cancel timers or schedules, select the required mode, and check the model’s owner’s manual for a manual-operation button. Some systems deliberately delay restarting for several minutes after being switched off.

If the display is blank, check whether lights and other equipment in the property still work. You may observe the position of a clearly labelled breaker or RCD, but do not remove a switchboard cover or repeatedly reset a device that operates again.

What the pattern can tell us

• Remote works but the indoor unit does not respond: the receiver, controller, power supply or internal electronics may need testing.
• Indoor unit responds but the outdoor unit does not start: confirm that the selected mode is actually calling for heating or cooling and allow any restart delay described by the manufacturer. If the outdoor unit still does not respond, the command, electrical supply or equipment needs testing.
• Breaker trips when starting: leave the air conditioner off and seewhy an air conditioner can trip a circuit breaker.
• Error code appears: record it exactly with the model number before resetting anything, then follow the model-specific error-code guidance.
• System stopped after a storm or outage: electrical protection or control damage is possible, but testing is needed before drawing a conclusion.

Preparing for a diagnosis

Photograph the model labels, controller display and switchboard labels without opening any covers. Note the last time the system worked and any noise, water, smell, outage or maintenance immediately beforehand.

Neighbourhood Electrical & Air can assess both the air-conditioning equipment and its electrical supply across Perth.