Hitachi "31" fault

[ronaldo9]

Hey guys

Have two split hitachi systems both identical.

Indoors 2x RCIM 2.0
Outdoors 2x RAS-2.5 (dont get excited i know see below)

System A works ok, no faults

System B had a faulty inverter board which needed to be replaced, we've had a couple of these under warranty. When you order these new boards they send you the entire control box, its all integrated. So i replaced the control box turned everything on and got a "31" fault. From above i remember that because the outdoors are 2.5hp and the indoors are 2hp you have to set DSW-3 on outdoor to identify it as a 2hp unit or else it wont run. Did this and still got fault code "31". I made sure all Dip switches were correct on both outdoor and indoor units. These units are not connected to a central controller and so do not need to have different refrigerant cycle number. They are just set to 0 on indoor and outdoor unit. I tried a few things with the capapcity settings, making sure to reset power to indoor and outdoor units after any changes as indoors can hold faults. Nothing worked.
Finally i swapped the control box from System A the good one with System B, which had the new control box. Just to be clear
System A- now has the replacement control box
System B - now has the old working control box from system A.

When i started up system B again(the one that had the 31 fault)iot worked fine. When i started System A i got a 31 fault. I double and trible checked the dip switch settings. I was on to Hitachi tech, they werent sure why the fault was occuring, there is obviously something up with the new control box, any ideas??

The 2.5hp outdoors were sent by mistake, we didnt have time to wait for new 2.0hp units so we installed them anyway.

[ronaldo9]

No takers on this one, ive been told this has happened once before, whatever way the board comes from the factory you have to set the dip swiches to the opposite of what you want?,,,,ill give it a try. the only problem is its a 8 hour round trip,,,ouch