Mine does not run if the temperature of the water is two degrees or more below the setting of the thermostat. For example, thermostat is set at 101. Pump runs at 100 or 101 degrees. Pump shuts off if water is 99. Don't ask me why, it just does.
Does your screen read "standard" in the lower right? If so, your pump should run if the temperature is as described. Push "mode" to make "standard" appear. It either "standard" or no reading on mine. No reading is summer mode on mine.
Hope that helps.