What was found
35 MINS INTO FLIGHT, FL350, -39C OAT- "L SIDE WINDOW" "OVERHEAT" LIGHT ON. QRH P6 3.5, OFF FOR 5 MINUTES, SWITCH ON - LT ON AGAIN. SWITCHED OFF REMAINDER OF FLIGHT. GROUNDED - YES. PER B737-800 FIM 30-41 TASK 809 WHCU BITE PASSES. HAS SENSOR FAULT IN HISTORY. WINDOW HEATER RESISTANCE CHECK GOOD. WINDOW SENSOR LUGS FOUND LOOSE. CLEANED AND REATTACHED L2 WINDOW SENSOR TERMINALS. PER FIM 30-41 TASK 811. WINDOW SENSOR PRIMARY TAP RESISTANCE CHECK GOOD AT 312 OHMS. THE BACKUP TAP (NOT IN USE) ALREADY TESTS BAD. CONNECTION LEFT ON PRIMARY TAP. WHCU BITE TEST GOOD. WINDOW HEAT SYSTEM OPS TEST GOOD. FAULTS RESET.