In order to combat the weirdness with the diode chiller temperature not reaching its desired set point
of 20 degC, I raised the set point to 21 degC.  This seems to have brought the chiller temperature
to ~19 degC.

    Trending the diode chiller temperature, one can see that there's an oscillation in the actual
temperature.  It might be to fool the system we ought to change the temperature set point to 22 degC.

From the trend data one can easily see the temperature oscillations that are apparent when one looks
at the chiller control panel.