Genuine Daikin 1700613 Outdoor Thermistor Set is the set of temperature sensors in the outdoor unit that give the system the readings it uses to run correctly through the cycle. When one starts to fail, the outdoor unit may struggle to hold output, run hot or cold, or stop and start at odd times. A genuine set reads temperature the way your Daikin expects, keeping the system accurate — where a non-genuine part can read off and leave it running incorrectly.