Hitachi multi problems

[billywizz]

Hi everyone, this is my first post so I hope you will go easy with me! Been visiting the forum for over a year and thought it was about time to have a go.
I've got a RAS-10FS2 two pipe outdoor unit connected to 7 indoor RPC units, all the indoor units are showing a 03 fault code and the operation lamp is flashing. The outdoor 7 segment display is illuminated and scrolling rapidly from 100 to 199 repeatedly, a similar unit on site which is running normally has no illuminated display here. My knowledge of Hitachi is limited so any guidance would be appreciated. In other posts I've seen loose connections in Change over boxes mentioned, are these the same as BS boxes in other systems?

[Inverter man]

O3 alarm on the indoor units indicates no comm to the O/U, the scrolling numbers on the O/U means the O/U is looking for the I/Us but will eventually display a flashing 03 alarm.
From the O/U terminals 1 and 2, the comms cable is a low voltage non polarity 2 core cable which daisy chains to each I/U terminals 1 and 2, connected order to the I/Us doesn't matter.
Initialy check the comms cable is plugged in at the O/U and there is not a break or short in the comms cable, also check the dip witch settings at the O/U, there should be some detail of dipswitch settings on the O/U electrical cover. Maybe you could connect only the 1st I/U to the O/U, if the O/U picks up the I/U you should see a 31 alarm at the O/U which is saying that the connected capacity between I/Us to O/U is not matched. If you can post your email address, I can forward you the relevent info for the system alarm which may help. Inverter man

[billywizz]

Cheers to MRcoolingMAGIC and Inverterman for your help, I will let you know how I get on.

[stuartwking]

Hi billy, Another thing to look out for is in your change over boxes there should be a blinking yellow led, i think its led 3., As it should be blinking at least once every ten seconds, no blinking means that unit ON the blink!,haha if you no what i mean.

[Chill doctor]

Hi
There are no change over boxes on an fs2, its a two pipe system.
i suggest as inverter man suggests, your problem is communications.

[billywizz]

Got back to site at last, weather warming up must have loosened the clients pockets. Metered out all the interconnecting wiring from outdoor unit up to third floor and found no continuity between condenser and first unit, second unit to third? Original cable did seem very flimsy and cores possibly to small. Ran new .75mm 2core and turned on all power supplies, now all units work normally. Could have been rodent damage or just poor cable. Thanks to all who posted advice.

[Inverter man]

Result, Cool!