ActronAir 2020-132B Digital Residential Indoor PCB provides indoor fan speed control, zone output switching, and wall controller communication for ActronAir split ducted systems, forming the primary control interface between the wall controller, zone outputs, and refrigeration circuit. Board degradation typically presents as intermittent fault codes or erratic operation before complete failure -- complete loss of indoor unit operation and zone control confirms the board rather than a sensor or wiring fault. Isolate power at mains before replacement -- live work on electrical components is dangerous and must only be performed by a qualified technician.