Storm and Blackout Help
Air Conditioner Not Working After Power Outage
Is your air conditioner not working after power outage or a summer storm? You are not alone. Blackouts, brownouts and lightning strikes regularly leave systems silent, blinking or showing a code. Often the fix is simple, such as waiting out a built-in restart delay or resetting a breaker. Sometimes, though, a power surge damages electronics. This guide helps you work out which situation you are in.
First Things First
Why Won’t My Air Conditioner Start After the Power Comes Back?
When mains power drops out and returns, an air conditioner goes through a restart process. The controller boots up, checks its sensors, and protects the compressor by waiting before it starts. During that wait the system can look dead even though nothing is wrong.
Beyond that, outages create other problems. The supply can flicker on and off several times, which may trip a circuit breaker or safety switch. Some systems forget their settings and sit in standby until you press the remote. In storms, a voltage spike can also damage a circuit board, a fuse or the outdoor inverter.
So the first task is to separate a normal delay from a real fault. The steps below do that in a logical order, starting with the easy wins.
Symptoms
What Does the Problem Look Like?
Owners describe a handful of common patterns after a blackout. Matching yours helps point toward the cause.
Often Simple to Fix
- Indoor unit lights are on but nothing happens for a few minutes
- Remote shows settings but the unit ignores it
- Wall controller screen is blank or showing the clock flashing
- Outdoor unit is silent while the indoor fan runs
- Timer or schedule settings have reset to default
May Need a Technician
- Breaker or safety switch trips again straight after reset
- Burning smell from the indoor or outdoor unit
- A communication or board error code on the display
- No lights and no response at all, even with power restored
- Outdoor unit buzzes or clicks but the fan never spins
- Wi-Fi module or app no longer connects
Notice whether other appliances on the same circuit are working. If lights and power points in that part of the house are dead too, the issue sits in your switchboard rather than the air conditioner.
Causes
What Are the Common Causes, From Simple to Serious?
Built-In Restart Delay
Inverter systems wait before starting the compressor after power returns. This protects it from starting against high pressure. The delay commonly lasts a few minutes, so patience solves many cases.
Settings Lost or Standby Mode
Many split systems power up into standby. Some have an auto restart feature that resumes the previous mode, while others need a fresh press of the remote. Ducted wall controllers may need the time and schedule reset.
Tripped Breaker or Safety Switch
Fluctuating power can trip the dedicated air conditioner circuit breaker or the residual current device. The system will stay off until it is reset at the switchboard.
Outdoor Isolator Switched Off
Occasionally someone switches the outdoor isolator off during a storm for safety, then forgets. Check its position before assuming a fault.
Blown Fuse on the Board
Indoor and outdoor control boards usually carry a protective fuse. A surge can blow it, leaving the unit completely dead. Replacing it is a job for a technician, as the board must also be checked for damage.
Communication Fault
A spike can damage the circuit that lets the indoor and outdoor units talk. The indoor unit then shows a communication code and the outdoor unit never starts.
Damaged Control Board or Inverter
The most serious outcome is surge damage to the main board, the inverter module or a fan motor driver. These parts are sensitive to voltage spikes, especially from nearby lightning.
Brand Differences
How Do Different Brands Behave After an Outage?
Restart behaviour and fault reporting vary from brand to brand. The notes below are general. Your user manual will confirm the details for your exact model.
Daikin
Many Daikin splits include an auto restart function that returns to the last setting once power is stable. A communication fault after a storm may display as Daikin U4, and an indoor board problem as Daikin A1.
Mitsubishi Electric
MSZ-AP and MSZ-EF wall units usually recover automatically. Indoor to outdoor communication issues on Mitsubishi Electric models can appear as Mitsubishi E6. Mitsubishi Heavy Industries uses a different code system, so check which Mitsubishi you own.
Panasonic
Panasonic systems typically resume after power returns, though the timer may reset. A storm-related communication fault often shows as Panasonic H11 when you run the check function.
Samsung
Samsung models, including WindFree, may need the SmartThings app to reconnect to Wi-Fi after an outage. Lost indoor to outdoor communication is commonly shown as Samsung E101.
Fujitsu
Fujitsu units, including the Lifestyle range, report faults with flashing lamp patterns. A serial communication fault is listed as Fujitsu 11, and a wired controller fault as Fujitsu 12.
If your code is not listed here, the main error codes page explains how to read faults for each brand.
Owner Steps
What Safe Steps Can You Take Right Now?
Work through this sequence once power is stable. Stop immediately if you notice a burning smell, scorch marks or smoke.
Wait Several Minutes
Give the system time to complete its restart delay. Many units start on their own without any help.Press the Remote or Controller
Turn the system on, select a mode and set a temperature. Fit fresh batteries if the remote screen is faint.Check the Switchboard
Look for a tripped breaker or safety switch labelled for the air conditioner. Reset it once. If it trips again, leave it off.Check the Outdoor Isolator
Make sure the weatherproof switch near the outdoor unit is in the on position.Do a Full Power Cycle
Turn the air conditioner breaker off for around five minutes, then back on. This clears many temporary faults.Look for Codes and Lights
Note any flashing lamps or codes on the display. They help a technician diagnose the problem quickly.Reconnect Smart Controls
If the app shows the unit offline, check your router has rebooted and follow the brand’s Wi-Fi setup steps.
Never open the unit’s covers, touch wiring or try to replace a fuse yourself. Electrical work on fixed appliances must be done by a licensed person. Our general air conditioner not working guide covers other reasons a system may stay off.
System Types
Does the Type of System Change What You Should Check?
Yes, a little. Split systems, multi head systems and ducted systems recover from an outage in slightly different ways, so it pays to know which one you have.
Wall Split Systems
A single indoor head paired with one outdoor unit. These usually have one breaker, one isolator and a handheld remote. Recovery is normally quick once the restart delay ends.
Multi Head Systems
Several indoor heads share one outdoor unit. If one head works and another does not, the outdoor unit is fine, and the issue is likely with that head’s board or wiring.
Ducted Systems
A ceiling or underfloor indoor unit with a wall controller and often a zone module. After an outage, the controller may need time to reconnect, and zones can lose their settings. Our ducted zone guide helps if only some rooms work.
Ducted systems also tend to have a separate circuit for the indoor fan coil and the outdoor unit. As a result, you may need to check two breakers at the switchboard rather than one. Look for labels such as air conditioner, AC indoor, AC outdoor or a room name.
Why Does the Wall Controller Show the Wrong Time?
Many ducted controllers keep time with a small backup battery or capacitor. After a long outage, that backup may run flat, so the clock resets and any heating or cooling schedule stops working. Simply set the time again and check that your programmed schedule is still saved. If the controller resets every time the power flickers, its backup may need replacing.
What If the Air Conditioner Runs but Feels Weak?
Sometimes the system restarts but only the indoor fan runs, blowing room temperature air. That usually means the outdoor unit has not started. It may still be in its protective delay, its breaker may be off, or a surge may have affected the outdoor board. Give it a little longer, then check the outdoor isolator and breaker before calling for help.
Storm Seasons
When Are Storm Outages Common in Australian Cities?
Severe thunderstorms bring most of the lightning-related surges, and they hit some capitals harder than others.
Brisbane and South East Queensland have a well-known storm season from late spring through summer. Afternoon supercells can bring hail, damaging winds and intense lightning. Suburbs across the north, such as Strathpine and Chermside, and the west around Ipswich often see outages during these events. That is also when air conditioners are working hardest, so failures hurt more.
Sydney gets its own storm season over the same months, with the western suburbs and Hills District frequently in the firing line. East coast lows can also bring prolonged wind and rain outages along the coast.
Melbourne has fewer tropical-style storms but does see strong cold fronts and summer thunderstorms. Adelaide experiences occasional damaging storms and has had widespread outages in the past. Perth’s summer storms are less frequent, though winter fronts can bring down lines in the hills and outer suburbs.
Prevention
How Can You Protect Your Air Conditioner From Surges?
No home can be made completely immune to lightning, but you can reduce the risk. Many owners in storm-prone suburbs take these steps.
- Ask a licensed electrician about a surge protection device at the switchboard
- Switch the system off at the remote when a severe storm is approaching
- Turn the system off before power is restored after a long outage, then restart once supply is steady
- Keep the outdoor unit clear of debris that wind may throw against it
- Check the outdoor unit for hail damage to fins and the fan guard after storms
- Keep a note of any fault codes that appear so a technician can review them
A plug-in surge board does not suit most hard-wired air conditioners, so protection is normally installed at the switchboard. An electrician can advise what is suitable for your home.
Technician Visit
What Will a Technician Check After a Power Outage?
If the system still will not run, a technician will trace the problem from the supply through to each component. A typical visit covers the following steps.
Confirm Supply Voltage
Checking power at the indoor and outdoor terminals to rule out switchboard or wiring faults.Read Fault History
Retrieving stored codes from the remote, controller or board diagnostics.Inspect Boards and Fuses
Looking for blown fuses, burnt tracks or damaged components on indoor and outdoor boards.Test Communication Wiring
Checking the interconnecting cable and the communication circuit between units.Check Motors and Compressor
Testing fan motors and compressor windings for surge-related damage.Advise on Repair
Explaining which parts need replacing and whether repair makes sense for the system’s age.
Find local help through Brisbane air conditioner repairs, Sydney air conditioner repairs, Melbourne air conditioner repairs, Adelaide air conditioner repairs and Perth air conditioner repairs. If storm damage is part of a larger insurance claim, a written report from the technician can be useful.
Safety
Is It Safe to Keep Trying to Run It?
A couple of restart attempts are fine. Repeatedly forcing a system on when a breaker keeps tripping is not. A tripping breaker is a safety device doing its job, and resetting it again and again can make damage worse.
Likewise, if you smell burning plastic, see scorch marks or hear crackling, isolate the system at the switchboard and leave it off. Wait for a technician to inspect it before using it again.
Open more detail
Brownouts, where voltage sags without fully dropping out, can be harder on equipment than a clean blackout. Motors may struggle to start, and electronics may reboot repeatedly. If your street has an unstable supply during a storm, it is sensible to keep the air conditioner off until it settles.
Some home insurance policies cover motor burnout or storm damage. Check your policy wording and keep any damaged parts the technician removes, along with their written findings.
If your system is older and needs a major board or compressor repair, the technician can talk through repair versus replacement in general terms, so you can make an informed choice.
Finally, keep in mind that a power outage can also reveal a fault that was already developing. A weak capacitor or a tired fan motor might cope with normal running yet fail during the stress of a restart. In that case the outage is the trigger rather than the root cause, and the technician will explain the difference.
Questions
Frequently Asked Questions
How long should I wait after a blackout before the AC starts?
Most systems have a restart delay of a few minutes. Wait at least that long before assuming there is a fault.
Why is my remote not working after a power cut?
The unit may be in standby or still booting up. Try again after a few minutes and check the remote batteries.
My breaker keeps tripping when I turn the AC on. What now?
Leave the breaker off. Repeated tripping signals an electrical fault that needs a licensed technician to find.
Can lightning damage an air conditioner without a direct hit?
Yes. A nearby strike can send a surge through power lines that damages boards, fuses or the inverter.
Should I turn my air conditioner off during a storm?
It is a sensible precaution. Turning it off at the remote reduces load and risk when supply is unstable.
Why does my app say the unit is offline?
Your router or the unit’s Wi-Fi module may need to reconnect. Restart the router and follow the brand’s pairing steps.
Why does only the indoor fan run after the outage?
The outdoor unit may still be in its protective delay, or its breaker or isolator may be off. If it never starts, a surge may have affected the outdoor board or the communication circuit, so book an inspection.
Will insurance cover a surge-damaged air conditioner?
Some policies do. Check your policy and ask the technician for a written report describing the damage.
Related Links
Which Related Guides Should You Read Next?
These pages may help, and our homepage covers air conditioning service Australia wide.
System Still Dead After the Storm?
Call us with the brand and any codes showing, and we will send a licensed technician to diagnose it.
Reviewed by AC repair and service specialist on 22 October 2026. How we write our articles