Common Air Conditioner Error Codes

Whether you have a ducted air conditioner, split system, multizone or a commercial air conditioning unit, you may see a dreaded error code appear on your master controller. Some may be an easy fix, such as simply resetting your air conditioner and clearing the onboard memory while others require professional assistance.

There are many possibilities as to why your master controller may be displaying error codes or why your system is not responding. Potential reasons across a range of air conditioners include:

  • The system needs re-gassing
  • Old age (wear and tear)
  • Technical faults
  • Unforeseen weather events
  • Animals damaging the system in the roof or the outdoor unit
  • Air conditioner not switched on at the control
  • The circuit breaker has tripped
  • Vermin may have chewed through controller wiring
  • Blown council service fuse
  • Your local power supplier may be doing works to your areas power supply
  • Internal fault in the air conditioner
  • Compressor delay after a restart
  • Delayed fan start on heating

If moulded case circuit breakers or earth leakage circuit breakers have tripped, do not reset the breaker immediately without first checking, or have your technician check for any problems with insulation of equipment. Resetting breakers without a check of insulation may cause damage to equipment.

By ‘resetting’ your air conditioner, what we mean is deleting the air conditioners on board memory to try a fresh restart. While not always successful, it is the first step in trying to save money with a service call. Some faults are caused by lightning strikes, blackouts and brownouts or various power fluctuations caused by any number of things and just may be the cause of your air conditioner shutting down for safety reasons.

How to reset your air conditioning error codes. (Note: we are NOT resetting circuit breakers
that have tripped.) Isolator Switch Master Reset. Go to your outdoor unit.
1. Locate the isolator switch on the unit or on the wall beside the unit, which looks like a
commercial on/off switch.
2. Turn the switch off and leave it off for an hour.
3. Turn the isolator switch back on after an hour.
4. Turn the unit back on from the master controller and see how the system runs.

Turning off the isolator switch will cut the power from the switchboard and clear the memory
of the air conditioning functions it was doing beforehand.


To find out more about fault codes the links below will give you some useful information from manufacture websites:


We’re only happy when your air conditioning system is performing at its best. We offer easy, fast and professional air conditioning repair service for commercial and domestic units in Canberra.

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