 The intrusion of coolant into the delicately balanced refrigeration system can cause expensive damage to components such as the freon compressor, and the reversing valve.Conceptually, mechanical freeze stats are constructed with a diaphragm, a capillary tube and bulb, and an electric switch.The capillary tube allows gas movement to and from the capillary bulb and the diaphragm with a fall or rise in temperature, respectively.