Added to page 1 schematics post: temperature and current sensor signal conditioning.
My crude little test data is not very useful to determine the cutoff temperature, but the reference voltage set point is at about 3V (3.042) with the Low Threshold at 2.6 and the High at 3.3V. This corresponds to a sensor resistance ranging from about 5k to 10kΩ, but i did not measure an intermediate temperature point to correspond to that range.
At room temperature i measured about 100 to 120kΩ, and you would not want the heatsink to get so hot as to boil coolant in the chill plate, so i would need to measure the slope somewhere between ambient and boiling water temperature. Maybe there is a standard curve for 100kΩ ambient thermistors.
The current sensor is an LEM hall-effect type. The gain of the current sense amplifier is about 1.7 and that signal is summed with some transistor logic that i will put all together on another sheet.