What was found
AT 36000 IN CRUISE L SIDE WINDOW OVERHEAT LIGHT ILLUMINATED RAN QRH AND LITE WENT OUT UNTIL APPROX 20,000 IN DES PER QRH TURNED OFF WINDOW HEAT SWITCH. GROUNDED - YES. PERFORMED B737-900 FIM 30-41 TASK 801 BITE TEST PASS. HISTORY SHOWED MULTIPLE SENSOR FAULTS. PERFORMED FIM 30-41 TASK 811 SWAPPED SENSOR POSITIONS FROM PRIMARY TO SPARE SENSOR ON L2 SIDE WINDOW OPS AND BITE CHECK PASS REF B737-900 AMM 30-41-00.