The Daikin-McQuay 6026873 PCB Control Board RXN18NMVJU is a replacement main circuit board designed for the Daikin RXN18NMVJU outdoor unit in compatible ductless mini-split HVAC systems. It receives signals from sensors and connected components, processes operating conditions, and controls functions such as the compressor, DC fan motor, electronic expansion valve, and four-way valve. https://www.partshnc.com/daikin-6026873-pcb-control-board-rxn18nmvju