Daikin RY200KUY1 u4 error code

Hello Everyone!

First time poster long time lurker , so please be nice to me :)

I have a issue that hopefully a daikin technician can help me with?

I have a Ducted AC Unit - Daikin RY200KUY1 with 2x Internal wired controllers BRC1B62.

History:
4 Weeks ago had a surge on the property and burnt the outdoor PCB - got that replaced with a new pcb after a daikin specialist came by and got it inspected etc.

Since then i cant get a hold of the specialist since the crazy heat in australia at the moment and theres a 1.5 week waiting to get a daikin techy which i cant just do in this heat.

So i changed the pcb etc and everything outside is ok in terms of error messages.

Issue:


Outside Unit:

Iv been reading service manuals and just maybe not understanding it properly.

Outside Unit has the HAP ( Green light blinking) and the H1 and H2 ( RED lights OFF) - so my understanding is that there is no issue with the outside unit but something to do with the inside - according to the service manual.

Inside Unit:


The two wired units ( BRC1B62) are wired up from top floor to bottom.

I kept getting the Error: Unit No. 0 U4 and Spanner/ eyetest icon blink on both units.

This error will only blink when i want AC on - but WILL not display with basic fan from the roof unit blower.

So i removed the 2nd controller ( BRC1B62) and kept just the one controller in MASTER mode ( behind the unit it requests i flick the switch to M) - Now only have 1 wired controller.


Temporary Solution:

Because i keep getting the error display on the wired unit controller and the outdoor AC wont turn on under NORMAL mode i have done the following according to the service manual:

- Running the outdoor unit under Emergency COOL mode
- Indoor Wired Controllers still blinking Error: Unit No. 0 U4 and Spanner/ eyetest icon blink on both units.
- Constant Cooling
- Only able to Turn on unit with this method and only the HAP ( Green blinking) - No other Red Light Errors - 3 Phase Circuit Breaker will turn ON and OFF the Outdoor Unit in Emergency COOL mode.

Everytime i would touch the Outdoor Unit i will allways turn off from the Switch Board and not at the Magnetic Switch Relay at the OutDoor Unit.

Any help will be very appreciated - with the heat and no techy available to come by i really need to get this fixed as i am worried running this way will damage the outdoor unit and having young kids around the house i cant leave for long time.

Thanks everyone for any help.

Have a Good Day!

when u set the 1 controller to master did you power it down first? have you got 2 flashing green lights on indoor pcb, if it works in test mode then possibly indoor board is damaged

did you need to set the dip switches on the pcb befor fitting

The U4 error message means that the indoor pcb cannot communicate with the outdoor pcb.

First thing to check after changing the pcb is that you wired the transmission cable correctly, i.e.
T1 to indoor T1
T2 to indoor T2
T3 to indoor T3

If you get 2 & 3 mixed up you will get an error.

Did you fit the capacity resistor on the replacement outdoor pcb?

Suspect that the indoor PCB may have become damaged with the power surge.

had a similar problem and it turned out after the power surge it changed the factory settings of the remote controller..
replaced outdoor board and indoor boards and still had problem and checked my wiring a hundred times over and still had fault
if you can get your hands on a spare remote controllers it would be worth a shot but if not the daikin tec talked me through changing the settings on the remote

he told me he never heard of it before