Start with the refrigerant gas: usually either Freon gas or Ammonia. In the compressor unit, this gas when compressed is heated. It passes then through condenser coils, where the gas is cooled to a liquid (giving off or exchanging heat). This cool liquid is then transferred to a large evaporator coil inside the used part of the refrigerator; the coil assembly is kept at a lower pressure. Evaporation under this reduced pressure requires heat to convert the liquid to a vapor; this heat is supplied by the air (and contents) inside the refrigerator, so that this vaporization process results in heat loss and a corresponding temperature drop. The cooled gas then returns to the compressor to repeat the cycle. So, in this chain of changes of state, the heat inside the refrigerator (that part where one wishes to keep its occupants cool) is removed during evaporation and is transferred to the moving Freon which then releases the heat at the condenser.
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