Temperatures in domestic refrigerators and freezers are
controlled by thermostats which turn the refrigeration system
(compressor) on when temperatures are too warm and off
when temperatures are satisfactory. The result is a cyclic on/
off operation during which temperatures repeatedly pull
down when the compressor is turned on and then rise again
when the compressor is turned off. When the compressor is
running, the power is generally very similar regardless of the
heat load, as the power of the compressor varies little while
switched on. However, under greater heat loads, it is the
length of time for which the compressor runs which increases
overall energy consumption.