As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
Received VENT EXTRACT FAULT shortly after takeoff. Crew experienced grinding noise, mild vibration and strong smoke smell. Returned to IAH and landed uneventfully. Found avionics cooling extract fan 18Q failed. Applied MEL 21-26-02 provisions and returned A/C to service.