Are you talking about the pushbutton control unit? Most all the brains of the system are in the pushbutton control unit. I have seen this referred to as the Climate Control Unit, or Climate Control Module.
If this is what you are referring to, it is extremely important to test the current draw of the auxilliary water pump. If the current draw is more than 1.3 Amps, replace the Aux. Water Pump at the same time. Excessive current draw on this unit is the most common reason for Climate Control Unit failure.