What was found
WHILE CRUISING AT FL360 THE LEFT FRONT WINDOW OVERHEAT LIGHT ILLUMINATED. TURNED L FWD WINDOW HEAT SWITCH OFF FOR 5 MINUTES AND THEN TURNED IT BACK ON PER QRH PROCEDURE AND THE OVERHEAT LIGHT ILLUMINATED IMMEDIATELY. GROUNDED - YES. FOUND LEFT FRONT WINDOW HEAT C/B OPEN ON P6-5 PANEL. ACCOMPLISHED GVI OF P6-5 PANEL. NO DEFECTS NOTED. ACCOMPLISHED C/B RESET PROCEDURE REF B737-900 AMM 20-60-01. ACCOMPLISHED B737-900 FIM 30-41 TASK 801. OPS CK GOOD. ACCOMPLISHED WINDOW HEAT CONTROL UNIT SYSTEM TEST AMM TASK 30-41-11-710-801. ALL TESTS PASS. NO HISTORY PAST 30 DAYS.