As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
L SIDE WINDOW OVERHEAT LIGHT ILLUMINATED AT CRUISE FL350. PERFORMED QRH 3.5 LIGHT DID STAY EXTINGUISHED. GROUNDED - YES. RESISTANCE CKS TEMP SENSOR & HEAT FILM NORMAL REF B737-900 AMM 30-41-21 TERM TAP CORRECT. DUE TO HISTORY REPLACED P5-9 WINDOW/PITOT HEAT MODULE & COIL CORD REF AMM 30-41-41 14 C/B OPEN & CLOSED OPS NORMAL.