Abstract: A refrigeration system including a pressure actuated switch for controlling the refrigeration compressor. The actuator of the switch is connected directly to the refrigerant line by a small capillary tube so that changes in refrigerant pressure effect changes in the position of the switch. Positioned between the pressure actuated switch and the refrigerant line is a bi-directional check valve which permits refrigerant pressure changes to be transmitted through the capillary line to the pressure actuated switch, but which functions to seal off the refrigerant line in the event of a break in the capillary tube.