I have an R407c City Multi system running 4 indoor units (PLFY-P63VKM-A). I have a fault code 002 2502 (Drain pump fault). None of the units are labeled up. Is there anyway i can find out which indoor unit is at fault. None of them have any water leaks on yet but i understand that 2502 can mean the water level is higher than normal and the drain pan or drain outlet could be blocked. Thanks