As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT SIDE WINDOW HEAT OVERHEAT LIGHT CAME ON DURING FLIGHT QRH DIRECT US TO TURN OFF (FOR 5 MINS) THEN TURN BACK ON, OVERHEAT LIGHT EXTINGUISHED. OPERATED NORMAL FOR REST OF FLIGHT. QRH DIRECTED INFORMATION ONLY WRITE UP. GROUNDED - YES. PERFORMED OPERATIONAL TEST OF LEFT SIDE WINDOW HEAT REF B737-800 AMM 30-41-00-710-801, OPS CHECK GOOD. INFO NOTED.