U5 Fault Daikin VRV ll

[Deano240]

Have a U5 fault keep coming up. strange thing is it runs up fine in the morning runs as normal then certain times when i look at the intellegent controller it says U5 fault on 3units thers about 30 units on this intellegen controller then theres a wall mount controller that controls the 3 units. If it was the PCB surely the fault would come up straight away and the unit wouldnt run? Could some one give me advice and do you think it is the PCB? i have to go back to the job out of hours and want to know what im looking for. Cheers

[hyperion]

Sounds as if it might be a fault on the control circuit between the three units units and the wall mounted controller. Check for a loose connection or it could be a setting error on the remote controller.

[Crash Pilot]

Check P1 p2 wiring loop for loose connection.
Test for break or short in cable.
If you have more than one controller on site swap them around and see if the fault transfers to the other unit. This will test the controller.
Make sure controller cable is away from current carrying cables (Noise interference).

[Deano240]

cheers guys. Am i right in thinking its deffinatly not the PCB?