It could be a thermocouple but its more likely to be an RTD. There are multiple types of thermocouple used in multiple applications. Yes it is the temperature sensor that is used to monitor/ control the fridge.
A thermocouple is an electrical device consisting of two different conductors forming electrical junctions at differing temperatures. A thermocouple produces a temperature-dependent voltage as a result of the thermoelectric effect, and this voltage can be interpreted to measure temperature.