Air conditioning and the refrigerator can be seen everywhere in our life. They have make our much easier and more convenient. But do you have a little knowledge about these machines,and do you have heard of the thermostat? Thermostat is a very important part in the air conditioning and refrigerator.It keeps the temperature in a stable level.pressure thermostat and liquid expansion thermostat are widely used in these machines.The snap action thermostat is often used to be switch to protect the electric power.Bimetal thermostat is also very popular in many electric products.With the thermostat in the machine,temperature can be controlled very easily.