How does a refrigerator make things cold?
A refrigerator does not create cold: it moves thermal energy from inside the cabinet to the room.
A closed loop
A refrigerant circulates in a closed loop. Pressure changes let it evaporate at low temperature and condense again at a higher temperature.
Inside: absorbing heat
In the evaporator, refrigerant evaporates while absorbing thermal energy from the air and food, cooling the cabinet.
Outside: releasing heat
The compressor raises the refrigerant pressure. In the condenser, the refrigerant releases heat to the room and becomes liquid again.
Why the back feels warm
The released heat includes both energy removed from the refrigerator and electrical energy used by the compressor, so the back can become noticeably warm.
What to notice in real use
Real devices are never ideal. Response time, insulation, sensor placement, seals, manufacturing tolerances and calibration all affect what you observe. Two appliances based on the same physical principle can therefore behave differently.
That is useful rather than confusing: once the core mechanism is understood, the remaining differences often come from engineering choices rather than from a different law of physics.
From observation to measurement
A useful scientific habit is to distinguish the quantity being measured from the way the instrument senses it. The display may show degrees, pressure or another familiar unit, while the sensor itself may respond to resistance, deformation, expansion or phase change.
Look at the mechanism, not just the object
A useful way to understand an everyday object is to follow a chain: what enters the system, which material or component responds, what physical or chemical change occurs, and what useful effect comes out. This separates the scientific principle from the casing and design.
The same principle often appears in very different objects. Once the mechanism is recognised, links between chemistry, materials, electricity, heat and mechanics become much easier to see.