How do refrigerator/freezer combinations with dual-thermostat control work with regards to the pump?

The thermostat is only supposed to control the frequency at which the pump turns on and off. How can there be two different thermostats for that?How do refrigerator/freezer combinations with dual-thermostat control work with regards to the pump?think of the two controls this way, one controls temperature of entire unit, like your house thermostat, and the other controls air flow from the freezer into the fridge, similar to your individual room vent controls.