ActronAir Coil Sensor (Outdoor) 1.2m Grey 3-Pin JST Connector monitors outdoor coil temperature on ESP Plus, AIRES, and Advance R32 residential split ducted systems, providing the coil temperature data the outdoor PCB uses for defrost management, capacity modulation, and refrigerant circuit protection. The grey 3-pin JST connector distinguishes this outdoor coil sensor from the white 2-pin indoor coil sensor -- connectors are keyed and cannot be cross-fitted, but confirming the colour and pin count before ordering prevents unnecessary returns. Isolate power at mains before replacing outdoor coil sensors.