I can't emagine why neutral should be switched but I would call their customer support to double check. Make sure it isn't 3 phase,stranger things have happened with overseas built equipment. Do not rely on terminal numbers,two of the three are hot and one of the three is neutral. If the terminals are not marked and you don't understand simple by looking,get an electrician. If they are not right when you turn it on you will let the smoke out of some things.

The outdoor unit may well be making 3-phase, but it will be variable frequency, in most cases, to drive the compressor. That means that transfer of the 3-phase to indoor would be pretty useless. You most likely have single phase to the indoor unit.

The install manuals for mine indicate a three-pole disconnect as well. I don't have any. This is an electrical code issue. You might contact your local building dept. to see if it is required.

Thanks, all. I found the detailed schematics of the indoor units and branch boxes (branch boxes drive the indoor units). Looks like terminals 1 and 2 provide the single phase 220V power supply. Terminal 3 is a serial communication line driven by an IC named HU2001R3. The receiver on indoor unit side is HI2003R3. HU2001R3 is driven by the NEC microcontroller uPD78F1164. I could not find the datasheets for HU2001R3, but it looks like it is a kind of parallel to serial converter and it uses a reference voltage (220V input voltage in this case) to generate the serial output. This means that terminal 3 is also operating at 220V. So, it looks like 3-pole disconnect is needed.

Actually, the 2& 3 wires are the control circuit on Fujitsu's. That is a neat system, when done according to specs.

I have not handled the HFI system from Fujitsu since its introduction. The Nat'l Elec Code requires a disconnect at the evaporator. I have never put them in. I don't want it beside the evaporator. I control service of my system at the outdoor disconnect. You decide if you want the disconnects, if the inspectors agree.