LG Multi-split system LM-3065H3L issue

Hi,

I have an LG multi-split (one condenser feeding 3 indoor units) model : LM-3065H3L
the problem is only one unit blowing cold air. the other 2 units blow just an ambient air temperature. on the outside unit only 2 piping seem to get cold and wet, obviously the only two piping feeding the working indoor unit. other two piping seem warm with no refrigerant flowing on them. I'm new on this system, i believe (not sure) the outdoor unit has only one compressor in it and each indoor unit should call for refrigerant when cooling is needed in that room. please to correct me if I'm wrong.

before going to the hassle of dismantling everything and troubleshooting I'd appreciate if someone can help me out to save energy and time with suggestions on where to look.. i couldn't find any technical manual on the internet that explains how does multi-split system technically work. so i can get an idea on what may be causing this issue.

thank you !

LG are notorious for sensor faults.
Could have dodgey air sensors on indoor units, try swapping it from the good one to see what happens.
If the sensors think the room temp is low they will not call for cooling.

Cheers,
Keza