ActronAir Compressor Discharge Sensor 100K@25degC monitors compressor discharge temperature on Advance R32 and AIRES residential split ducted systems, providing the discharge temperature data the outdoor PCB uses to manage compressor capacity limits and protect the refrigerant circuit from overheating. The 100K ohm at 25 degrees C NTC thermistor rating is specific to the Advance and AIRES system PCBs -- substituting a sensor with a different thermistor rating causes incorrect temperature readings and may result in either premature capacity limiting or inadequate overtemperature protection. Isolate power and recover refrigerant before replacing any compressor discharge sensors.