Is compressor running constantly? Superheat readings are taken directly off of beacon board located in box on front of evap.. Superheat should be running 8-10 deg. Instructions for board are inside cover. This board is somewhat self diagnostic and may be flashing an error code(probably a bad sensor). Make sure if you replace sensor(s) you use the latest version from beacon. These sensors are prone to water intrusion and failure. These units are tricky to diagnose if your not familar with them, as they try to refrigerate even when they sense a problem, rather than shutting down w/total loss of refrigeration.