As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IAH - FLT 3994 - PILOT REPORTED THAT WHILE ON THE GROUND, THERE WAS SMOKE IN THE COCKPIT. MAINTENANCE INSPECTED THE AIRCRAFT AND FOUND THE LEFT GROUND COOLING FAN TO BE FAULTING. MAINTENANCE DISPATCHED THE AIRCRAFT BACK TO SERVICE UNDER MEL 21-51-2, OF THE CONTINENTAL EXPRESS MEL/CDL MANUAL. (X)