How to Reset Your Air Conditioning Unit When It’s Not Working

If your air conditioner suddenly stops working, shows an error, or refuses to cool properly, one of the simplest troubleshooting steps is performing a hard reset.

Just like computers and other electronic devices, air conditioning systems can occasionally lock up due to electrical glitches or communication errors. Resetting the system often clears these temporary faults and restores normal operation.

In this guide we explain:

• how to reset an air conditioner safely
• when resetting the system can fix problems
• how to reset split system and ducted air conditioners
• how to reset popular brands like Samsung, Daikin and Mitsubishi
• when a reset will not solve the issue

How to Reset an Air Conditioner

The safest way to reset an air conditioner is to turn the unit off, switch off the outdoor isolator or circuit breaker, wait 30 minutes, and then turn the system back on. This allows the internal electronics and control board to fully reset.

Why Resetting an Air Conditioner Works

Modern air conditioners rely on electronic components such as:

• PCB control boards
• temperature sensors
• inverter controllers
• communication modules

Sometimes these components experience temporary software or electrical lock-ups.

Resetting the system clears stored faults and restarts the internal electronics.

If the problem is temporary, the system may begin working normally again.

Signs Your Air Conditioner May Need Resetting

You may need to reset your air conditioner if you notice:

• the system suddenly stops running
• flashing lights or error codes appear
• the air conditioner runs but does not cool
• the remote control stops responding
• the system shuts down after a power outage

In many cases, a reset can restore normal operation.

Step-by-Step: How to Reset a Split System Air Conditioner

Follow these steps to perform a hard reset.

Step 1 – Turn Off the System

Use the remote control or wall controller to switch the air conditioner off.

Step 2 – Locate the Outdoor Unit

Find the outdoor condenser unit located outside your home.

Most Australian installations include a power isolator switch next to the unit.

Step 3 – Turn Off the Isolator Switch

Switch the isolator to the OFF position.

This disconnects the system from the electrical supply.

Step 4 – Wait 30 Minutes

Leave the system powered off for at least 30 minutes.

This ensures the internal control board fully resets.

Step 5 – Turn Power Back On

Switch the isolator back to ON and restart the air conditioner.

Check whether the issue has been resolved.

Resetting an Air Conditioner Without an Isolator

Older air conditioners may not have an outdoor isolator.

In this case you can reset the system using the electrical switchboard.

Reset Using the Circuit Breaker

• Locate your home’s switchboard.
• Find the circuit breaker labelled air conditioner.
• Turn the breaker OFF.
• Wait 30 minutes.
• Turn the breaker back ON.

This performs the same reset as an isolator switch.

Resetting a Ducted Air Conditioner

Ducted systems follow a similar reset process but usually have a central control system.

Reset Steps for Ducted Systems

• Turn the system off at the wall controller.
• Locate the outdoor unit isolator.
• Switch the isolator off.
• Wait 30 minutes.
• Turn power back on and restart the system.

If the problem persists, the issue may involve zoning controls or the compressor.

Resetting an Air Conditioner After a Power Outage

Power outages can cause air conditioners to enter protection mode.

When power returns, the system may not start immediately.

What to Do

• Turn the system off.
• Switch the isolator or breaker off.
• Wait 30 minutes.
• Turn power back on.

This clears any electrical protection faults.

Brand-Specific Air Conditioner Reset Instructions

Different manufacturers may have slightly different reset procedures.

Resetting a Samsung Air Conditioner

Samsung air conditioners sometimes display flashing lights or error codes.

To reset a Samsung AC:

• Turn the unit off using the remote.
• Turn the outdoor isolator off.
• Wait 30 minutes.
• Restore power and restart the system.

If error codes remain, the system may require professional diagnosis.

Resetting a Daikin Air Conditioner

Daikin systems may stop working due to sensor errors or communication faults.

To reset a Daikin unit:

• Turn off the air conditioner.
• Switch off the isolator.
• Wait 30 minutes.
• Restore power.

This clears many temporary faults.

Resetting a Mitsubishi Air Conditioner

Mitsubishi split systems are generally very reliable but may occasionally require a reset.

The reset process is identical:

• Turn the system off.
• Turn the outdoor isolator off.
• Wait 30 minutes.
• Turn the system back on.

Air Conditioner Troubleshooting Flowchart

If resetting your air conditioner does not solve the problem, use the following troubleshooting process.

This process helps eliminate common issues before scheduling repairs.

Common Problems That Resetting May Fix

Problem	Why Reset Helps
AC not turning on	clears controller fault
AC flashing lights	resets error code
AC blowing warm air	resets refrigeration cycle
Remote not responding	resets communication
System stopped after power outage	clears protection mode

Problems Resetting Will NOT Fix

A reset only clears temporary faults.

It will not fix mechanical or electrical failures such as:

• compressor damage
• refrigerant leaks
• capacitor failure
• fan motor failure
• PCB board damage

If your air conditioner continues malfunctioning after a reset, professional repair may be required.

Preventing Air Conditioner Problems

Many air conditioner issues can be avoided with regular maintenance.

Monthly Maintenance

• clean air filters
• inspect air vents
• check remote batteries

Every 6 Months

• inspect drain lines
• clean outdoor unit
• check refrigerant lines

Annual Professional Service

• electrical inspection
• refrigerant pressure testing
• evaporator coil cleaning
• fan motor maintenance

Regular servicing keeps the system running efficiently.

Final Thoughts

Resetting an air conditioner is one of the simplest troubleshooting steps and can often resolve temporary system faults.

However, if problems persist after a reset, the issue may involve electrical components, airflow restrictions or refrigeration faults that require professional attention.

Regular servicing and early diagnosis help keep your air conditioning system operating efficiently and prevent costly repairs.

Expert Air Conditioning Troubleshooting in Brisbane

If resetting your air conditioner does not fix the problem, it may indicate a more serious fault.

At Sun City Air, our Brisbane air conditioning technicians diagnose and repair a wide range of AC issues including:

• PCB control board faults
• compressor failures
• capacitor replacement
• refrigerant leaks
• electrical problems

If your air conditioner is not operating correctly, our team can inspect the system and provide a free quote for air conditioning repairs in Brisbane, Australia.

Frequently Asked Questions

How long should I leave my air conditioner off to reset it?

Most technicians recommend leaving the air conditioner powered off for at least 30 minutes. This allows the control board and internal electronics to fully discharge and reset before restarting the system.

Will resetting an air conditioner fix cooling problems?

Resetting an air conditioner can fix temporary electronic faults or system lock-ups. However, if cooling problems are caused by dirty filters, refrigerant leaks or mechanical failures, the reset alone will not resolve the issue.

Should I reset my air conditioner after a power outage?

Yes. After a power outage, some air conditioners enter a protective shutdown mode. Turning the system off and performing a reset can clear this protection and allow the system to restart normally.

Is it safe to reset an air conditioner yourself?

Yes, performing a reset using the isolator switch or circuit breaker is safe if done correctly. Always turn the system off before disconnecting power and wait at least 30 minutes before restoring electricity.

When should I call an air conditioning technician?

If resetting the system does not resolve the issue, or if the air conditioner displays persistent error codes, unusual noises or poor cooling performance, a technician should inspect the system to identify underlying faults.