What was found
LEFT FWD WINDOW OVERHEAT AMBER LIGHT ON OVERHEAD (AND MASTER CAUTION LIGHT CAME ON AFTER 2 HOURS AT CRUISE. COOLED FOR 5 MINUTES, TURNED SWITCH BACK ON, OVERHEAT CAME ON IMMEDIATELY AND STAYED ON. TURNED SWITCH OFF AND KEPT OFF FOR REMAINDER OF FLIGHT. ACFT GROUNDED. FOUND CIRCUIT BREAKER OPEN ON P6-11 PANEL, INSPECTED CIRCUIT BREAKER & PANEL AREA, NO DEFECTS NOTED. CHECKED RES OF SENSOR AND WINDOW, BOTH CHECKED NORMAL. REPLACED WINDSHIELD HEAT CONTROL UNIT AS A PRECAUTION IAW 30-41-11. GROUND VERIFICATION SUCCESSFUL IAW 30-41-00.