Daikin FFQ50BV1B

[Peter_1]

Daikin FFQ50BV1B + RXS50BVMB.
Fault Code U4, seems to be bad communication.
Strange phenomena: on same main power supply but on a different breaker, the VD controlled compressor (grounded) of a VRV failed also this morning.
For the Daikin pro's: what do you think, change both (in- and outdoor) PCB boards?
Does someone has the manual of FFQ50BV1B and RXS50BVMB

[brunstar]

This is strange that both systems have gone down sharing the same power supply.
check to see if the varisters are blown on the outdoor printed circuit board, this will indicate over voltage or a dropped neutral.

[Peter_1]

No, no varistors blown, only 1 compressor grounded.
Call for the split was in teh late afternoon and for the VRV around 10 o'clock this morning. This is the second VFD compressor in 5 months and the 3th in 12 years on the same site with total 11 outdoor VRV units.
In that building on the same main supply are at least 200 PC's connected and testing devices in electronic labs. If there should be a problem with the supply, then I suspect also faults in other systems apart from the VRV's.