Air Conditioner Error Codes Decoded for Daikin, Mitsubishi, Fujitsu and Samsung

A flashing light or a strange code on your air conditioner can be unsettling, especially on a hot Melbourne afternoon. The good news is that the code is your system’s way of telling you what it has noticed. Once you know how to read it, you can decide calmly whether it is a quick fix or a job for a licensed technician.

This guide explains the most common air conditioner error codes for Daikin, Mitsubishi, Fujitsu and Samsung systems, plus what you can safely check yourself.

A quick note before you start: error codes differ between brands, model series and even controller types. Treat the tables below as a general guide and check your model’s manual for the exact meaning.

What to Do When Your Air Conditioner Shows an Error Code

Before diving into brand-specific codes, work through these safe first steps:

Write down the code. Note the letters and numbers, or count the flashes of each indicator lamp. Take a photo if you can.
Turn the system off and restart it. Switch it off at the remote, wait about 30 seconds, then switch the power back on at the wall or switchboard. A brief power glitch can trigger a temporary code.
Check the basics. Clean the filters, make sure vents are not blocked, and clear leaves or debris from around the outdoor unit.
Stop if the code returns. A code that comes straight back usually points to a real fault.

Please do not remove panels, touch wiring, or handle refrigerant yourself. Electrical work needs a licensed electrician, and refrigerant handling in Australia requires an ARC-licensed technician.

Daikin Error Codes

Daikin units show codes on the wired controller or through indicator lamps on the indoor unit. These are the ones we see most often.

Code	What it usually means
A1	Indoor unit control board (PCB) fault
A5	Freeze-up or pressure protection, often linked to dirty filters or poor airflow
C4	Indoor heat exchanger (coil) temperature sensor fault
E5	Compressor overload or lock protection in the outdoor unit
E7	Outdoor fan motor fault
U4 or UF	Communication fault between the indoor and outdoor units

If you see A5, clean the filters and check airflow first. If you see U4, a reset can help, but a repeat code usually means a wiring or control board issue that needs testing.

Need help with your system? Our team offers Daikin air conditioning service in Melbourne.

Mitsubishi Electric Error Codes

Mitsubishi Electric systems show codes on the wired controller, or through a pattern of flashing lamps on the indoor unit. Count the flashes and pauses carefully, as the pattern is the code.

Code	What it usually means
E6 or E7	Communication fault between the indoor and outdoor units
P6	Freeze or overheat protection has activated
P8	Pipe temperature fault, often related to airflow or refrigerant conditions
U3 or U4	Outdoor temperature sensor (thermistor) open or shorted

Communication codes such as E6 can be caused by wiring faults, power surges after a storm, or a control board issue. If a reset does not clear it, it is time to book a technician.

If your unit is a Mitsubishi, see our Mitsubishi air conditioner service in Melbourne.

Fujitsu Error Codes

Most Fujitsu wall-mounted systems report faults through the lamps on the indoor unit. The pattern is usually read as the number of Operation lamp flashes, then the number of Timer lamp flashes. Lamp colours vary by model, so confirm in your manual.

Operation + Timer flashes	What it usually means
1 + 1	Serial communication error
2 + 2	Indoor pipe (coil) temperature sensor fault
4 + 1	Indoor room temperature sensor fault
6 + 3	Inverter error

Good to know: if all three lamps flash a few times and the unit will not start, it is often not a fault at all. According to Fujitsu General Australia’s support guidance, this commonly happens when the weekly timer has been switched on by accident. Check your remote for the word “WEEKLY”, cancel the timer, and try again.

For repairs on these systems, visit our Fujitsu air conditioner service in Melbourne.

Samsung Error Codes

Samsung air conditioners display codes on the indoor unit’s panel. Some of them are friendly reminders rather than faults.

Not faults:

Code	What it means
CF	Time to clean or replace the filters
CL	Auto clean function is running
dF	Defrost mode is running, which is normal in heating

Faults that need attention:

Code	What it usually means
E101	Communication error between the indoor and outdoor units
E121	Indoor room temperature sensor error
E122	Indoor heat exchanger sensor error
E154	Indoor fan error
E201 or E202	Communication error between the indoor and outdoor units

Samsung advises contacting an authorised service provider for fault codes that involve sensors or components. Our Samsung air conditioner service team in Melbourne can diagnose these on site.

Quick Reference: Common Causes Across All Four Brands

Most error codes fall into a few simple groups:

Communication faults (Daikin U4, Mitsubishi E6, Fujitsu 1+1, Samsung E101): wiring, power surges or control board problems
Sensor faults (Daikin C4, Mitsubishi U4, Fujitsu 4+1, Samsung E121): a failed or disconnected temperature sensor
Freeze or overheat protection (Daikin A5, Mitsubishi P6): usually airflow, dirty filters or low refrigerant
Fan faults (Daikin E7, Samsung E154): a stalled or failing fan motor

How to Prevent Error Codes

Regular care prevents many of the faults above. Two Australian Government resources are worth bookmarking:

The Victorian Government’s top 10 energy saving tips include practical advice on using your heating and cooling efficiently.
The Australian Government’s Energy Rating site explains how dirty filters reduce airflow and efficiency, and how each degree of extra heating or cooling adds to your running costs.

Beyond that, we recommend:

Cleaning filters every few months, or more often in dusty homes
Keeping the outdoor unit clear of leaves, boxes and debris
Booking a professional air conditioner service and repair at least once a year

When to Call a Technician

Call a licensed technician if:

The same code returns after a reset
The breaker keeps tripping
You notice ice on the indoor unit, a burning smell or water leaking inside
The code points to a sensor, compressor, fan motor or communication fault

If your system stops on a very hot or cold day, our 24/7 emergency air conditioning repair service is here to help.

Is It Time to Replace Your System?

If your unit is older and faults are becoming frequent, a newer, more efficient system may cost less over time. Explore our split system installation, multi-head split systems, ducted air conditioning and reverse cycle air conditioning options. You can also check whether you are eligible for the VEU rebate.

Air Conditioner Repairs Across Melbourne’s South-East and Bayside

Kelvinaire is based in Mulgrave and services homes and businesses across Melbourne. Whether you own a Daikin, Mitsubishi, Fujitsu or Samsung, we can help with diagnosis, repairs and servicing in your suburb:

Not sure if we cover your area? Browse all Melbourne service areas.

Frequently Asked Questions

Can I clear an air conditioner error code myself?

Sometimes. Turning the unit off for about 30 seconds and restarting can clear a temporary glitch. If the code returns, the system has detected a real fault and needs a technician.

Do error codes mean the same thing on every brand?

No. Codes are set by each manufacturer and can vary between model series, so always check your manual or ask a technician.

Why is my air conditioner flashing lights but not showing a code?

Many split systems use lamp flashes instead of a display. Count the flashes of each lamp and note the pauses, as that pattern is your code.

Is it safe to keep running my air conditioner with an error code?

It is best not to. Running a system with an active fault can cause further damage. Switch it off and arrange a service.