For electric heat, hot gas or compressor shutdown defrost. The Sikelan MD-DT40 Series Auto Voltage Defrost Timer is applicableto air defrost (compressor shutdown) and electric or hot gas defrost systems where the defrost cycle is terminated by the timer lfthe coil is frost-free, the timer can also be terminated by temperature or pressure switches before the programmed defrosttermination time has been reached. The time termination functions as a fail-safe and terminates the defrost cycle if thetemperature or pressure switch fails to do so.