As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
L SIDE WINDOW HEAT OVERHEAT LIGHT ILLUMINATED AT CRUISE ALTITUDE (FL350). PERFORMED QRH PROCEDURE (PAGE 3.3) OVERHEAT LIGHT STAYED EXTINGUISHED. CHECKED PER FIM 30 41 TASK 811 STEP F (1)(2) AND G. SENSORS BOTH CHECK GOOD. 284 OHMS. REPLACED L SIDE WHCU. REF MM 30 41 00 000 801 & 30 41 11 400 801. OP CHECK NORMAL.