As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING FLIGHT, THE PILOT TURNED ON HEAT-VENT BLOWER AND REPORTED HEARING AN UNUSUAL HIGH PITCHED WHINE AND UNUSUAL SMELL AND THEN SHUT OFF THE UNIT. MAINTENANCE PERSONNEL COULD NOT DUPLICATE THE NOISE, BUT DID SMELL AN ODOR. UNIT WAS REPLACED AND CARBON WAS FOUND IN THE UNIT FROM THE BRUSHES WHICH WERE WORN TO HALF-LIFE.