Serial fault mitsubishi elec. MUH 12 V

[RBM]

Hello
wondering if anyone can help I have a unit with serial fault and would like to know how to fault find serial faults I think it uses 12 volt DC from indoor unit but I dont really know how to properly test. Any help would be much appreciated.

[seadanzig]

hi rbm you need to let us know the model and the fault your having to be able to help. serial can be communication between controller and indoor or indoor to outdoor

[install monkey]

at the outdoor unit
12v accross 1 and 2 compressor signal
12v ccross 2 and 3 reversing valve energised- for cooling mode- i think
if your not getting 1v there check your indoor unit to see if your getting 12v leaving the indoor unit
if you are then test your interconnect cabling is ok

[RBM]

I know its late install monkey but thank you for your help

[assailant]

I know its late install monkey but thank you for your help

so whatd you end up doing?