A fridge does not make cold, it moves heat somewhere else

Everything here earned its place by changing an outcome. Nothing about refrigeration is included to round the number up.

The cycle in four steps

A compressor raises the pressure of a refrigerant gas, which raises its temperature above room temperature. That hot gas passes through coils outside the cabinet, gives up heat to the room and condenses into a liquid.

The liquid then passes through a restriction into a low-pressure region, where it evaporates and absorbs heat from inside the cabinet. The gas returns to the compressor and the loop repeats, with heat carried from inside to outside every time round.

Where the heat goes

Everything removed from the interior is released into the room, plus the energy the compressor itself consumed. A fridge therefore heats the kitchen slightly, and leaving the door open cools nothing and warms the room. The coils need airflow to release that heat, which is why a fridge pushed tight against a wall or boxed into a cupboard works harder.

The short version: dusty coils have the same effect and are one of the few user-serviceable efficiency items on the appliance.

Insulation decides the duty cycle

The compressor runs only to counteract heat leaking in through the walls, the seals and the door openings. Better insulation and a good door seal reduce that leak, so the compressor runs less and consumes less.

A seal that no longer grips a sheet of paper placed in the door is leaking continuously and is a cheap repair. A full fridge holds its temperature better than an empty one because the contents store cold, though it does not reduce the underlying leak.

Freezers, frost and defrosting

Moisture in air entering the cabinet condenses and freezes on the coldest surface, which is the evaporator. A layer of frost insulates that surface from the air it is meant to cool, which reduces efficiency measurably. Frost-free designs periodically warm the evaporator with a small heater and drain the meltwater away, spending energy to avoid the frost penalty.

Mechanically, that is why frost-free freezers use slightly more energy but never need manual defrosting.

Compressor types and the noise

Traditional compressors run at a fixed speed and switch on and off, which is the familiar clunk and hum cycle. Variable-speed compressors run continuously at a low rate matched to demand, which is quieter, holds temperature more steadily and is more efficient.

The gurgling and ticking sounds from any fridge are refrigerant moving and metal expanding, not faults. A compressor that runs constantly at full speed and never cycles indicates a leak, a failing seal or a blocked coil.

Implementations differ, and vendors are not obliged to document the differences.

Reading energy labels honestly

Labels are measured under a standard test with defined ambient temperature and no door openings. Real consumption depends on kitchen temperature, how often the door opens and what is put inside warm. A fridge in a hot garage or next to an oven consumes considerably more than its label suggests.

Label schemes and their scales differ by region, so compare within a market rather than across them.

Everything above, in order of what to do first

1. The cycle in four steps. A compressor raises the pressure of a refrigerant gas, which raises its temperature above room temperature.
2. Where the heat goes. Everything removed from the interior is released into the room, plus the energy the compressor itself consumed.
3. Insulation decides the duty cycle. The compressor runs only to counteract heat leaking in through the walls, the seals and the door openings.
4. Freezers, frost and defrosting. Moisture in air entering the cabinet condenses and freezes on the coldest surface, which is the evaporator.
5. Compressor types and the noise. Traditional compressors run at a fixed speed and switch on and off, which is the familiar clunk and hum cycle.
6. Reading energy labels honestly. Labels are measured under a standard test with defined ambient temperature and no door openings.

The takeaway

It is a heat pump with a door. Give the coils air and check the seal.

Once you know what it is trading away, the design stops looking arbitrary.