Good question. You've touched upon an important question that can be explained with thermodynamics. Believe it or not, Freon cools a refrigerator in the same way that your sweat cools your skin. Freon is a liquid in a refrigerator coil because it is under very high pressure. When it expands, Freon is actually changing from a liquid to a gas. This is an example of a phase change that is endothermic.Endothermic means that the Freon takes in heat. So Freon doesn't get colder as it expands, it actually warms up! But it does so by taking in heat from the things around it making them colder. The same thing happens when sweat evaporates (or phase changes from a liquid to water vapor) from your skin. It takes in body heat from your skin making you cooler while it gets enough energy to turn into water vapor.