[ShawnJones]

Well it's probably a variable resistor, the resistance will either increase or decrease depending on the temprature. Unplug the chiller, put an ohm meter across the black leads (not the header pins) and measure the resistance on the lines, heat or cool the tank and measure the resistance. It should move one way or another. Once you establish the resistance direction based on temprature, create a harness with a fixed resistor from radio shack so the chiller thinks that the water is always hot. Plug your new harness on the header pins and allow the controller to supply power to the chiller as needed.

UNPLUG THE CHILLER FIRST

Hope it helps, let me know if you need any help.

Shawn