As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER 5-10 MIN IN CRUISE FLIGHT AT FL 340, R SIDE WINDOW HEAT ANNUNCIATOR ILLUMINATED. FOLLOWED QRH AND CYCLED SWITCH OFF FOR 5 MINUTES,THEN BACK ON. LIGHT REMAINED EXTINGUISHED. GROUNDED - YES. ACCOMPLISHED WHC BITE WITH NO CURRENT FAULTS. CONTOLLER HAD LOGGED #1 SENSOR, REF B737-900 AMM 30-41-00.