Mitsubishi Heavy Industries Air Conditioning Fault Codes Explained
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Mitsubishi air conditioning units alert owners to errors using LEDs: the indoor circuit board (ICB) has a green LED (GLED) and a red LED (IRLED), and the outdoor circuit board (OCB) has the same. We are going to look at common faults and how the LEDs in the system can alert you to an error.
Unless stated, these error codes and signals apply to all R410A air conditioning units.
No error code, RLED on ICB and OCB stays off and the GLED on ICB and OCB keeps flashing:
Thankfully, everything is running as normal.
No error code, all LEDs off
There is no mains power detected – check to see if your power is switched on. Alternatively, you may have a power failure on your premises.
No error code, ICB RLED: flashes 3x, ICB GLED: flashing, OCB RLED: off, OCB GLED: flashing:
The connections of remote controller wires X & Y are reversed, as are the connections of wires Y & Z. The remote controller wiring is an open circuit, and if the X wire is broken, you will hear a beeping sound but no indication. For a broken Z wire, there is no beep or indication.
Error code: LCD flashes continuously or off, ICB RLED: off, ICB GLED: flashing, OCB RLED: flashes 2x, OCB GLED: flashing
There is an open circuit or the wiring is poorly interconnected, either indoors or outdoors.
Error Code: E1
Unit: FD Split 1, 2 Series R410A – ICB RLED: off, ICB GLED: stays off or on, OCB RLED: off, ICB GLED: flashing
There is a failure of the indoor circuit board or CPU – it may need repairs or replacement.
Unit: KX4 & KXR4 Series R410A – ICB RLED: stays off/on, ICB GLED: stays off/on, OCB RLED: off, OCB GLED: flashing
Indoor circuit board failure or a failure with the CPU.
Unit: FD Split 1, 2 Series R410A – ICB RLED: off, ICB GLED: flashing, OCB RLED: off, OCB GLED: flashing
- In a group control system, the power supply to at least one indoor unit has switched off
- The remote controller wire Y is an open circuit
- The wires of remote controllers X and Y are reversed
- There is a fault with the indoor or remote controller printed circuit board
- Electrical noise may be interfering with the system
Unit: KX4 & KXR4 Series R410A – ICB RLED: off, ICB GLED: flashing, OCB GLED: off, OCB GLED: flashing
- The wiring of the remote controller connected to A and B is faulty
- The A and B wiring is connected in a closed loop
- The printed circuit board of the indoor unit runs away
Error Code: E2
Unit: KX4 & KXR4 Series R410A
ICB RLED: flashes 1x, ICB GLED: flashing, OCB RLED: off, OCB GLED: flashing
- There is a duplication of indoor unit addresses
- There are more than 49 indoor units connected to a single network
Error Code: E3
Unit KX4 & KXR4 Series R410A
ICB RLED: flashes 2x, ICB GLED: flashing, OCB RLED: off, OCB GLED: off
The outdoor unit is not receiving any mains power, either due to a power failure the power being switched off
ICB RLED: flashes 2x, ICB GLED: flashing, OCB RLED: off, OCB GLED: flashing
The outdoor unit has an incorrect address setting
ICB RLED: flashes 2x, ICB GLED: flashing, OCB RLED: stays on/off, OCB GLED: undefined
The outdoor unit is not receiving mains power
Error Code: E5
ICB RLED: flashes 2x, ICB GLED: flashing, OCB RLED: flashes 2x, OCB GLED: flashing
Communication error between the outdoor and indoor units
ICB RLED: flashes 2x, ICB GLED: flashing, OCB RLED: off, OCB GLED: flashing, either regular or irregular
Failure with the outdoor unit’s microcomputer
Unit: FD Split 1, 2 Series R410A – ICB RLED: flashes 2x, ICB GLED: flashing, OCB RLED: off, OCB GLED: off
Control failure of the outdoor unit, and also there may be a fault with the inverter parts
Unit: KX4 & KXR4 Series R410A – ICB RLED: flashes 2x, ICB GLED: flashing, OCB RLED: off, OCB GLED: off
- Power failure to the outdoor unit
- A communication error between the outdoor and indoor units
- The A and B wiring may be reversed
Need Help with your Mitsubishi System?
If you are in need of further assistance with your Mitsubishi air conditioning fault codes, then contact the experienced, skilled team at Airway Air Conditioning on 0800 859 5174 and we will be more than happy to help you with whatever you need.