Nope, 30 minute delay didn't help. After 30 minute delay, the freezer turned on, then the temperature dropped below the hysteresis and the heat turned on.
Here's how I had my iobridge module setup with the onboard rules engine and some x-10 modules to handle switching on/off the freezer and heater. It may spur an idear or two:
I created a rule that turned OFF either the freezer of heater when the temperature was within a "dead zone". For example, if the temperature was between 66° and 68°, a rule would execute that sent off commands my heater or freezer (via x-10). If the temperature went 1° above or below the dead zone, either the freezer or heater would turn ON. The dead zone band is wide enough to prevent an output from turning on right after the other turns off.
This makes me think about about the idea of having a separate setpoints and hysteresiss for each cooling and heating output. I wonder if this would prevent an output turning on right after another one was turned off?
My brain hurts thinking about this...