Refrigerants work the same way perspiration works on our bodies. When our body gets hot, we sweat. As this sweat evaporates, the heat dissipates and our bodies get cool. Refrigerators and air conditions use the same principal, but they use other gasses that work better than water. A compressor compacts the gas (Freon or ammonia) and this makes it hot. The gas is allowed to cool off, but it is still under pressure. As this gas is allow to expand and evaporate it gets very cold.