So you need to Pick a problem: make your food cold

But you can't make cold. Nobody can. You can only move heat out.

1. So a refrigerant boils in a pipe inside the fridge, soaking up heat from your food.
2. But that gas is colder than your kitchen, and heat only flows from hot to cold.
3. So a compressor squeezes it until it's hotter than your kitchen, and coils on the back pour the heat into the room.
4. But it's still under high pressure, and too warm to chill anything.
5. So it's forced through a thin tube. The pressure drops, and it's freezing cold again.
6. But left running nonstop, it would freeze your milk.
7. So a thermostat switches the compressor off at around four degrees Celsius.

Your fridge never makes cold. It just moves heat, from your food into your kitchen.