Abstract: The invention relates to a pressure responsive electric switch assembly of a type used as evaporator thermostats for refrigerators. In this unit an actuating element for operating a switch is held in equilibrium by two springs acting in opposition to a bellows which is connected to a temperature sensor capsule containing a liquid-vapor filling. An abutment arrangement is provided for the springs so that, despite a constantly rising pressure in the bellows, the actuating element operated by the bellows has a zero or null displacement range which corresponds to a substantial intermediate pressure range to which the bellows is subjected by the temperature sensor. As there is no movement by the actuating element in this intermediate range, there is an avoidance of wear which would otherwise be caused by this movement.