The single thick 3-core cable supplies the mains power input to the control board and an output wire to the pump. This can be left alone. The two small 2-core wires go into a single 3-pin connector from the thermistors (temperature sensors). This connector can be pulled off from the control circuit board.

Now you can reassemble the fridge without attaching the thermistor cables. Now when you turn on the fridge, you should hear the pump working (it's quite quiet) for 15 mins every hour i.e. a constant 25% duty cycle, irrespective of the temperature.