First we need to conduct a short survey of the devices of the refrigerator.

If this is a classic refrigerator (without the No Frost system), it represents the following system:

The compressor absorbs refrigerant from the evaporator, filtering, and sends to the condenser. In this process the gas (freon) is very hot. The compressor is located at the bottom of the refrigerator.

In the condenser the refrigerant is cooled and becomes liquid.

The next phase includes several steps during which liquid refrigerant again passes into the gaseous state, but as a result of this action is already happening on a cooling space inside the refrigerator. At this stage, involved such elements of the refrigerator, as the capillary and the evaporator.

Steps are repeated until the desired temperature set by the thermostat, and when it reaches the motor of refrigerator compressor stops.

After some time the temperature in the refrigerator begins to rise, thanks to a certain mechanism of the motor of the compressor starts again and the cycle starts again.

In refrigerators of the old sample capacitor is integrated in the rear panel. Modern refrigerators are designed so that the condenser is located in the side panels.

The heating of the side walls in a modern refrigerators is due to the presence of the capacitor, because during work it is very hot. However, during a break at work, when reaching the desired temperature, the condenser cools down. Therefore, if you pay attention to the heating of the walls of the refrigerator, you will notice that this process is temporary, but periodic.

As for refrigerators with No Frost system, they have a slightly different structure, but the mechanism of switching-off of the capacitor when the desired temperature is still the same. Therefore, the side wall of the refrigerator No Frost (or Frost Free) also tend to heat up.