Need help!

[andyc425]

hey guys im on site engineer at a call centre no air con tools on site with me,iv got u4 fault on 3 systems the temp dropped from 21 cooling to 16 i no what the fault is but what i dnt no is how to fix it any advice ?

[andyc425]

iys daikin by the way and they were set on 21 cooling 22 heating

[NoNickName]

Communication fault between indoor and outdoor

[andyc425]

yeh i no the fault how do i fix it?

[NoNickName]

Check communication between indoor and outdoor. Check wiring does not go along together with power cables. Switch off and on to try resetting communication.
If everything else fails, it may be the PCBs have suffered a power surge and the three need to be replaced.

[andyc425]

nice one fella job done