This is a BRAND NEW ICP/Heil/Tempstar/Comfort Maker/Carrier/Bryant/Payne Heat Pump Defrost Sensor. The ICP Part # is 1173697 and the Carrier/Bryant/Payne # is HH18HA277A (found on the side of the sensor). Rated at L80-50. When a defrost sensor goes bad the heat pump will often turn to a solid block of ice (although this is not the only ice causing failure). Thanks for looking and good luck!
Sensors detect events or changes in their environment, and then relay the information to another device, typically a control board.
1173697 HH18HA277 HH18HA277A