What was found
DURING CRUISE WITH LEFT ANTI-ICE ON, THE LEFT ICE PROTECTION TEMPERATURE ANNUNCIATOR LIGHT ILLUMINATED. PERFORMED COM AND LIGHT WENT OUT. WHEN RIGHT SYSTEM WAS LATER SHUT DOWN BEFORE CROSSFEED CLOSED, THE RIGHT ICE PROTECTION TEMPERATURE ANNUNCIATOR LIGHT ILLUMINATED. FLIGHT RETURNED TO DTW AND LANDED WITHOUT INCIDENT. CHANGED THE LEFT AND RIGHT AUGMENTATION VALVE, ANTICIPATOR, AND THERMOSTAT. PERFORMED ICE PROTECTION SYSTEM OPERATINAL CHECK. CHECKED OK.