Error Code Library
Actron Air Conditioner Error Codes
Actron air conditioner error codes appear on the wall controller when a ducted or split system detects something outside its normal limits. This guide explains how Actron numbers its faults, which controller shows which code, and what you can safely check before a licensed technician takes a closer look.
Start Here
What Do Actron Air Error Codes Actually Tell You?
Actron Air is an Australian manufacturer, and a large share of its installed base is ducted. That matters, because most of the hardware sits in a roof cavity or on a side path, out of sight. The wall controller is the only part many owners ever look at. When the system protects itself or loses track of a sensor, the controller is where the warning lands.
An error code is a short label for a condition the control board has detected. It is not a diagnosis in itself. For example, a sensor code says the board is reading an impossible value from a thermistor. It does not say whether the thermistor, its plug, the cable run or the board is at fault. A technician still has to measure and confirm.
Even so, the code is genuinely useful. It narrows the search, it tells you whether the fault is likely indoor or outdoor, and it helps you decide how urgent the job is. Writing it down before you reset anything is the single most helpful thing an owner can do.
All Brand Error Codes
Browse our full error code library across the major air conditioning brands sold in Australia.
Ducted System Servicing
Find out what a full ducted service covers, from the return air filter to the outdoor coil.
General Troubleshooting
Work through common symptoms such as weak airflow, odd noises and water leaks.
Controllers
Which Actron Controller Do You Have?
Actron has used several generations of wall controller. The same number can mean slightly different things depending on which one is on your wall, so identifying it first saves confusion later. Look at the shape of the unit, the screen style and any model label on the back plate or in the user manual.
Que Controller
A touchscreen platform paired with the ESP Platinum ducted range, including the Que Platinum models. Actron’s fault reference lists codes that are also viewable in a technician menu on this controller.
Neo Controller
A wall controller Actron pairs with a broad range of its ducted systems, including the Classic and Advance series. It shows numbered E codes on the display.
L Series Controllers, Including LM7 and LR7
Actron lists these as compatible with Classic, ESP Plus, ESP Ultima and Advance split ducted systems. They are common in homes with older ducted installations.
WC-02 Wired Controller
Used with a range of Actron split and ducted products, including the Serene and UltraSlim series. Its code set is quite different from the larger ducted controllers, so read its codes against its own table.
If you cannot tell which controller you have, a clear photo of the screen while the code is showing is enough for a technician to work it out.
Structure
How Are Actron Fault Numbers Organised?
On the main ducted ranges, Actron uses an E followed by a number. Lower numbers tend to cover the basics, such as room and coil sensors, communication and the main refrigerant pressure switches. Higher numbers, often in the twenties and beyond on inverter models, relate to the variable speed drive that runs the compressor. Those drive codes cover things like overcurrent, overvoltage, drive temperature and internal protection.
Older controllers sometimes show the same fault with a leading zero, such as E09 instead of E9. Treat these as the same code. The Que platform also shows some faults under a technician menu number, which is why the indoor to outdoor communication fault can appear as both E5 and E51 depending on where you look.
The WC-02 wired controller is the exception. It follows a split system style code set with letters as well as numbers, such as EE for a water level problem. Because of this, an E3 on a WC-02 does not mean the same thing as an E3 on a Que or Neo controller. Each of our code pages notes which controllers the meaning applies to.
Open more detail
Actron publishes a product fault code reference that groups codes by product family, such as ESP Platinum, ESP Que Platinum, Advance, Classic, ESP Digital, Serene and UltraSlim. Within each family the numbering is fairly consistent, but there are differences between families. The pressure codes are a good example. On some older Classic and ESP Digital systems a single code covers high pressure, low pressure or a phase problem together, while newer variable speed systems split these into separate switch and sensor codes.
This is why our pages describe each code in general terms and flag where the meaning shifts by series. A technician will confirm the exact meaning against your model number before replacing any part.
Code Table
What Do the Common Actron Codes Mean?
The cards below summarise the codes we have written detailed guides for. Each summary is general, and the linked page explains the causes, the safe checks and what a technician tests.
E1
On the WC-02 controller used with Serene and UltraSlim systems, E1 points to lost communication between the indoor and outdoor units.
E3
On Que, Neo and L Series controllers, E3 relates to a sensor, usually the room temperature sensor. On Serene and UltraSlim systems with a WC-02, Actron links E3 to the indoor fan instead.
E4
On ESP Platinum, Que Platinum, Advance and Classic ducted systems, E4 flags the indoor coil inlet sensor.
E5
On ESP Platinum, Classic, ESP Digital and LM7 setups, E5 means the indoor and outdoor units have stopped talking to each other.
E6
On Que, Neo and L Series controllers, E6 relates to compressor discharge temperature running too high.
E7
Across Que, Neo and L Series controllers, E7 points to the outdoor coil temperature sensor.
E8
On Que, Neo and L Series controllers, E8 points to the outdoor discharge temperature sensor.
E9
On Que, Neo and LR7 controllers, E9 is linked to low refrigerant pressure. Some older systems use it for a combined pressure or phase fault.
E51
On LR7 controllers, Advance and Classic 2 systems, and in the Que technician menu, E51 means indoor to outdoor communication has been lost.
EE
On the WC-02 controller, EE is a water level alarm, which usually means the condensate drain is not clearing.
Detailed Guides
Where Can You Read About Each Code in Depth?
Choose the code showing on your controller. Every guide is written for Australian homes and explains what is safe for you to check and what needs a licensed technician.
Actron E1 Error Code
Communication loss on WC-02 controlled Serene and UltraSlim systems.
Actron E3 Error Code
Sensor fault on Que, Neo and L Series controllers.
Actron E4 Error Code
Indoor coil inlet sensor on the main ducted ranges.
Actron E5 Error Code
Indoor and outdoor communication error on ducted systems.
Actron E6 Error Code
High compressor discharge temperature.
Actron E7 Error Code
Outdoor coil sensor fault.
Actron E8 Error Code
Outdoor discharge sensor fault.
Actron E9 Error Code
Low pressure trip on the refrigerant circuit.
Actron E51 Error Code
Communication loss reported by LR7, Advance and Que systems.
Actron EE Error Code
Water level alarm on WC-02 controlled systems.
More Codes
What About Codes Not Listed Above?
Actron systems can show many more codes than the ones we have covered in detail. We only publish a full guide when we can confirm a meaning clearly. For the codes below, Actron’s own published fault reference gives a meaning, and we summarise it here so you know roughly where the problem sits. Treat these as a starting point, not a verdict.
Pressure and Refrigerant Codes
- E11 on ESP Platinum, Que Platinum, Advance and Classic 2 systems is listed as the outdoor high pressure switch having tripped.
- E12 on ESP Platinum, Que Platinum and Advance systems is listed as a high pressure sensor reading open or short circuit.
- E14 on ESP Platinum and Que Platinum systems is listed as condenser pressure running too low.
- EC on Serene systems is listed as refrigerant leak detection.
Fan, Sensor and Drive Codes
- E01 on Advance and Classic 2 systems is listed as an indoor fan speed feedback fault.
- E2 on ESP Digital systems is listed as the indoor coil outlet sensor.
- E15 on ESP Platinum, Que Platinum and Advance systems is listed as a communication fault with the variable speed drive.
- Codes from the twenties upward on inverter ducted models generally relate to the compressor drive, covering current, voltage and temperature protection.
Why Is There No Separate Page for E10?
E10 is a pressure related code on Que, Neo and LR7 controllers, but Actron’s own published material describes it in two different ways. Its online help pages link E10 with high refrigerant pressure. Its product fault reference lists E10 on ESP Platinum, Que Platinum and Advance systems as a low pressure sensor reading open or short circuit. Because those descriptions do not agree, we have not written a separate guide that might point you the wrong way.
What both descriptions share is the important part. E10 concerns the refrigerant pressure circuit in the outdoor unit, and it is not something an owner can fix. Clear the outdoor unit, check the filter, reset once, and if E10 returns, book a licensed technician. Read our E9 low pressure guide for background on how Actron pressure protection works.
If your code is not here, note it down along with the controller type and the outdoor unit model number. That combination lets a technician look up the exact entry for your system before they arrive.
Reading Codes
How Do You Retrieve an Actron Error Code?
In most cases you do not need to do anything special. The code appears on the wall controller as soon as the fault is detected, often alongside a warning symbol or a flashing screen. Some controllers keep a fault history that a technician can scroll through.
Look at the Controller Screen
Note the exact characters, including any leading zero or letter. E9 and E09 are the same, but EE and E3 are very different.Take a Photo
A phone photo captures the code, the controller style and the time. It is far more reliable than memory.Check Whether It Clears
Some protection codes clear by themselves once conditions settle. Note whether it returned, and how long the system ran before it did.Record the Model Numbers
The outdoor unit has a rating plate on its side. The model number there tells a technician which code table applies.Note What Was Happening
Write down whether the system was cooling or heating, the weather, and anything unusual such as a storm or a power cut.
On Que systems, a technician can also open a service menu to view stored faults. Owners do not need to use that menu, and it is best left to the person doing the repair.
Safe Checks
What Can You Safely Check Yourself?
A handful of simple checks are safe for any owner and occasionally clear a nuisance fault. Anything beyond these belongs with a licensed technician. Ducted systems carry mains voltage, and the outdoor unit holds refrigerant under pressure, so please do not open panels or covers.
- Turn the system off at the controller, then switch it off at the circuit breaker. Wait a few minutes and restore power.
- Check the switchboard for a tripped breaker or safety switch, and note which one if it has tripped.
- Open the return air grille and look at the filter. If it is clogged with dust, wash or replace it according to the manual.
- Walk around the outdoor unit. Clear leaves, garden clippings, stored items or overgrown plants away from the coil and the fan grille.
- Look for the condensate drain outlet outside and confirm it is dripping during cooling, not blocked or crushed.
- Make sure enough zones are open. Running with most zones closed can upset airflow on some systems.
- Check the controller has power and the screen is clear. A blank or flickering screen is worth mentioning when you book.
If the code comes straight back after a reset, stop resetting it. Repeated restarts against a protection fault can strain the compressor.
Australian Conditions
Why Do Some Codes Show Up More in Certain Weather?
Australia gives ducted systems a hard time. Long runs of hot days push outdoor units to their limits, and a roof space in summer can be far hotter than the air outside. High pressure and high discharge temperature codes tend to cluster around heatwaves, especially when the outdoor coil is dirty or crowded.
Humid summers in Brisbane and Sydney load up the drain system, which can bring on water level alarms. Coastal suburbs in every capital deal with salt air, which slowly corrodes coil fins and electrical connections. Inland dust, common around Perth and Adelaide in dry spells, clogs filters and outdoor coils. Summer storms bring power interruptions and surges, which are a frequent trigger for communication codes.
Melbourne adds its own twist. Heating runs hard through winter, so outdoor coil sensors and defrost related faults get a real workout. Knowing the season you saw the code in helps a technician think about the likely cause.
Getting Help
When Should You Book a Technician?
Book a visit if the code returns after a reset, if the breaker trips again, if you notice burning smells or buzzing, or if water is leaking through a ceiling. Pressure, discharge and drive codes almost always need professional testing. Sensor and communication codes can be simple, but they still involve live wiring inside the units.
Rapid Air Cooling books air conditioning repairs and dispatches licensed technicians across the major capitals. The technicians we send hold the licences their work requires, including ARCtick licensing for any refrigerant handling. We are not Actron Air and we are not an authorised Actron dealer. If your system is still under the manufacturer’s warranty, it is worth contacting Actron first.
For local help, see our pages for air conditioner repairs in Sydney, repairs across Melbourne, Brisbane repairs, Perth repairs and Adelaide repairs. For ducted servicing in each city, try Sydney ducted service, Brisbane ducted service, Perth ducted service and Adelaide ducted service. Our main page covers air conditioning service Australia wide.
Prevention
Can Regular Servicing Reduce Error Codes?
Servicing will not prevent every fault, but it removes many of the common triggers. Clean filters keep airflow healthy across the indoor coil. A clean outdoor coil lowers head pressure and discharge temperature on hot days. Clear drains stop water alarms. Tightened connections reduce the loose terminals that cause intermittent communication faults.
A service visit also gives a technician the chance to notice early signs, such as a sensor reading that drifts, a fan bearing that hums or corrosion starting on a terminal strip. Catching these on a mild day is far less stressful than losing cooling in the middle of a heatwave. Our ducted air conditioning service page explains what a typical visit covers.
Questions
Frequently Asked Questions
Are Actron error codes the same on every controller?
No. The main ducted controllers, such as Que, Neo and the L Series, share a similar numbering style, but the WC-02 wired controller uses a different set. Always read a code against the controller showing it.
Is E09 the same as E9?
Yes. Some controllers display a leading zero. The number is what matters, along with the product family.
Will turning the power off clear the code?
It may clear the display, and some protection faults reset after a pause. If the underlying problem is still there, the code will return, usually within minutes or hours of running.
Can I keep using the system with a code showing?
It depends on the code. Many protection codes stop the compressor on purpose. Forcing repeated restarts is not wise. Each of our code guides explains whether limited use is reasonable.
Why does my code only appear on very hot days?
Heat raises refrigerant pressure and compressor temperature. A dirty outdoor coil, poor airflow or a borderline refrigerant charge may only show up when the system is pushed hardest.
Do you need my model number before booking?
It helps but is not essential. The outdoor unit rating plate and a photo of the controller let the technician prepare, and they can confirm everything on site.
Are you connected to Actron Air?
No. Rapid Air Cooling is an independent booking service. We arrange licensed technicians who work on Actron and other major brands.
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Reviewed by AC repair and service specialist on 22 October 2026. How we write our articles