As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT FORWARD WINDOW HEAT OVERHEAT ANNOUNCIATOR ILLUMINATED. RAN QRH, LIGHT ILLUMINATED AGAIN. GROUNDED - YES. PERFORMED B737-900 FIM 30-41 TASK 812 SELECTED WINDOW SENSOR SPARE POSITION NO HELP. OVERHEAT LIGHT ON FOUND C/B WINDOW HEAT POWER LEFT FRONT P6-12, B9 OPEN. RESET TO CLOSE. PERFORMED WHCU SYS TEST. TEST NORMAL. NO WINDOW HEAT LIGHT ILLUMINATED IAW B737-900 AMM 30+-41-11-710-801.