What was found
WINDOW HEAT "OVERHEAT LIGHT" LEFT L SIDE, ILLUMINATED IN FLIGHT AND REMAINS ILLUMINATED AFTER PERFORMING QRH CHECKLIST. GROUNDED - YES. PERFORMED B737-800 FIM 30-41 TASK 811 FOR THE L2 WINDOW, WHCU FAULTS SENSOR CURRENTLY AND IN FAULT HISTORY. TEMPERATURE SENSOR RESISTANCE OUT OF LIMITS. REF L/P 60035425, L2 WINDOW ALREADY ON SPARE SENSOR. REMOVED W0420-1001-20 FROM TERMINAL #2 TO #1 PER B737-800 WDM 30-40-11 AND B737-800 AMM 56-12-11-400-801 STEP F. (9) REMOVED AND REPLACED L2 SLIDING WINDOW REF AMM 56-12-11-400-801. OPS & LEAK CHECK GOOD.