As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING GROUND GPU POWER OPERATION THE FREON AIR CONDITIONER BEGAN SMOKING INSIDE THE ACFT. THE AC UNIT APPEARS BURNED AND CHARRED. NO FIRE WAS NOTED FOLLOWING REMOVAL OF POWER FROM THE ACFT. INSPECTED THE FREON AIR CONDITIONING UNIT AND FOUND THE MOTOR/BRUSHES ARE BURNED. ARMATURE BAD AND NO TENSION ON BRUSHES. BURN DAMAGE CONFIRMED TO INSIDE MOTOR. REPLACED MOTOR.