ActronAir 2040-006 Fault Detection Board is installed in the outdoor unit of ActronAir split ducted systems and controls indoor fan speed control, zone output switching, and wall controller communication. When this board fails, complete loss of indoor unit operation and zone control -- replacing it with the 100% Genuine ActronAir 2040-006 restores all factory system functions without reconfiguration. Isolate power at mains before replacement -- live work on electrical components is dangerous and must only be performed by a qualified technician.