Intermittent U4 Error on Daikin FXAQ50MVE

[lek2k]

I live in an apartment with two wall mounted units, FXAQ50MVE and FXAQ32MVE connected to an outdoor unit 4MXS80EVMA located in a room on the roof. The strange thing is we only get a U4 error on both aircon units when use would be heavy in our building (i.e. on a very hot day). All other times it works :o/ Everyone in the building that I have asked does not have this problem.

Eg. During the heat wave in Sydney last week it did not work at all times of the day. As soon as the cool change came in on Sunday it started to work again without the U4 error.

What could be causing this problem ?
Thanks.

[install monkey]

undersized mains or voltage drops?

[airconboy]

i got called to something similar recentley,this was two cassettes when they was in full heating got the same but sometimes tripped,i turned out the site electrician put wrong size circuit breaker when unit was ramped up in full heating this would happen check what the previous post said i think he is correct one of the two

[Obi Wan]

FXAQ50MVE is a VRV indoor unit with an EEV.

4MXS80EVMA is a multi split with EEVs on the outdoor unit.

Do you have the correct combination or have the indoor units been modified in someway?

Regards

Obi Wan