Daikin VRV U9 Fault

[maxcool]

Hi Guys, I have a job on tomorrow which is an investigation into a U9 fault (system error between indoor and outdoor). Unfortunately the system label is not present but I believe it to be either a RESYP10KJY1 or RSXP10K7W1 on 407c. The system has 6 internal units and a number of box's within the ceiling. I don't generally have a great deal to do with VRV systems but could this be down to a loss of communication and most likely just require re-addressing? I am not too familiar on the best way to re-address these units. Any advice would be great before I start looking into it tomorrow!

[The Viking]

First thing to check,

Is there power to all the indoor units and BC boxes...

Then if you power the outdoor unit down and back up again is the fault still there...
Is it U9 on all the indoor units or is there one with a different problem?

[maxcool]

I wasn't able to gain access to the bc boxes however all indoor units appeared to have power. The rooms have been made available for me tomorrow in order to view boxes. The U9 fault is on every control on the system. Thanks

[frank]

Someone has turned off the power to one of the indoor units or a fuse has blown on one of the indoor fused spurs

[AbsoluteWDJ]

Hi Guys, I have a job on tomorrow which is an investigation into a U9 fault (system error between indoor and outdoor). Unfortunately the system label is not present but I believe it to be either a RESYP10KJY1 or RSXP10K7W1 on 407c. The system has 6 internal units and a number of box's within the ceiling. I don't generally have a great deal to do with VRV systems but could this be down to a loss of communication and most likely just require re-addressing? I am not too familiar on the best way to re-address these units. Any advice would be great before I start looking into it tomorrow!

Check all mains power to both BS and Indoor units, also check F1-F2 terminal block this includes field side and Daikin side of both indoor and BS units.