Did you rig up an external temp controller and if you did, where is the sensor? Or are you using the refrigerator as-is? If the latter, and the chamber is really well insulated, I'd doubt it would run continuously all night - unless you keep opening the door
. I would think that by using the refrigerator's thermometer, it will sense that it's gotten cool enough early and shut off. Then as the heat-redistributes it will kick back on. I don't know what the overall effect will be on the compressor since afterall it is having to cool a larger area.