I would doubt that "internal thermostat" is the right term. It sounds like

a modern electronic one and I would think they would use a sensor which

then interfaces to the control electronics, ie there is no separate themostat.

Thank you for that and sorry if my term thermostat was wrong: You are absolutely correct, what is in this GE PGB918SEM is a temperature sensor. It doesn't govern anything at all in the way a thermostat would: It just READS as you correctly note