Check Method 1
1. When the timer cancel button is held down for 5 seconds, 00 indication appears on the temperature display section.
2. Press the timer cancel button repeatedly until a long beep sounds. A short beep and two consecutive beeps indicate non-corresponding codes. The code indication changes in the sequence shown below.
3. When you hear the long beep, see the code on the indicator. It is the error code and description of fault is shown in the table below.
4. To return to the normal mode, hold the timer cancel button down for 5 seconds. When the remote controller is left untouched for 60 seconds, it also returns to the normal mode.
Check Method 2
1. Press the center of the TEMP button and the MODE button at the same time. The left-side digit will blink.
2. Press the TEMP up or down button and change the figure until you hear the beep.
3. Diagnose by the sound.
beep : The left-side digit does not correspond with the error code.
beep beep : The left digit corresponds with the error code but the right-side digit does not.
long beep : Both digits correspond with the error code.
4. Press the MODE button. The right-side digit will blink.
5. Press the TEMP up or down button and change the figure until you hear the beep.
6. Diagnose by the sound.
beep : The left-side digit does not correspond with the error code.
beep beep : The left digit corresponds with the error code but the right-side digit does not.
long beep : Both digits correspond with the error code.
7. When you hear the long beep, see the code on the indicator. It is the error code and description of fault is shown in the table below.
8. Press the MODE button to exit from the diagnosis mode.
9. Press the ON/OFF button twice to return to the normal mode. When the remote controller is left untouched for 60 seconds, it also returns to the normal mode.
Error Codes and Description of Fault
System
00 Normal U0 Refrigerant shortage U2 Low-voltage detection or over-voltage detection U4 Signal transmission error (between indoor and outdoor units) U7 Signal transmission error (on outdoor unit PCB) UA Unspecified voltage (between indoor and outdoor units) UH Anti-icing function in other rooms
Indoor Unit
A1 Indoor unit PCB abnormality A5 Freeze-up protection control or heating peak-cut control A6 Fan motor or related abnormality C4 Indoor heat exchanger thermistor or related abnormality C9 Room temperature thermistor or related abnormality
Outdoor Unit
A5 Anti-icing function E1 Outdoor unit PCB abnormality E5 OL activation (compressor overload) E6 Compressor lock E7 DC fan lock E8 Input overcurrent detection EA Four-way valve abnormality F3 Discharge pipe temperature control F6 High pressure control in cooling H0 Compressor sensor system abnormality H6 Position sensor abnormality H8 CT or related abnormality H9 Outdoor temperature thermistor or related abnormality J3 Discharge pipe thermistor or related abnormality J6 Outdoor heat exchanger thermistor or related abnormality J8 Liquid pipe thermistor or related abnormality J9 Gas pipe thermistor or related abnormality L3 Electrical box temperature rise L4 Radiation fin temperature rise L5 Output overcurrent detection P4 Radiation fin thermistor or related abnormalityIn our case, remote controller display was U4. It means Signal Transmission Error (between Indoor and Outdoor Units). The data sent from the outdoor unit cannot be received normally, or the content of the data is abnormal. Supposed causes are
1. Defective outdoor unit PCB
2. Defective indoor unit PCB
3. Wiring error
4. Disturbed power supply waveform
5. Breaking of the connection wires between the indoor and outdoor units (wire No. 3)
When the service guys came and checked our aircon, it was found that wire 3 was broken due to erosion at the connection point on outdoor unit. They suggested to replace the whole wire set in our system. I thought it was not necessary. After they peeled away one inch of outer layer and connected back, the system was OK. Interestingly, only third wire for all indoor units were eroded. It looks there must be DC voltage in that wire and it may be acting as electrode. So, I think the same thing will happen again.
2013 Jun 10 Update :
The system has been OK so far. It might not be electrode problem according to a comment on this blog post which said Daikin does not use DC for the signal. It might be because of the bad quality wire that the contractor used. I can now guess why they insisted to change the whole wire set :P Thanks to those who wrote comments in this post.2014 Feb 10 Update :
The same problem happened again in another indoor unit. This time, it was caused by faulty outdoor unit PCB. The said the cost to change the PCB is around 800 SGD.Reference:
Malfunction code chart
Service Manual
