An inquiry with Technotrans about the chiller controller yielded the information that provided the software version the controller is running is the same, they ought to be interchangeable. We have always had to provide the serial number of the affected chiller in order to get a replacement controller. The controller for the diode chiller (S/N 63793) was swapped with the one sitting in the mechanical room (S/N 44806) that underwent some tests and was the chiller used before. The chiller started up okay. No oscillations were observed in the chiller output temperature. Jeff/Jason/Peter