Automated systems and methods for testing the efficacy and reliability of distributed temperature sensing (DTS) system. The DTS system has a fiber optic sensing cable laid out on a structure to be monitored, and a DTS unit for sensing temperature along a sensing line at locations thereof. The DTS unit is optically coupled to the sensing cable. The sensing cable is optically coupled to a test cable to form the sensing line. Also provided, is a cooling device for cooling the test cable. A controller periodically actuates the cooling device to thereby test the efficacy and reliability of the DTS system. A relay configured for communication with the DTS unit and the controller is operable to trigger an alarm condition in response to a signal received from the DTS unit indicative that a temperature drop in the sensing line at a location thereof has been detected.