As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT REPORTED AIR CONDITIONER INOPERATIVE. UPON INVESTIGATION, FOUND PULLEY SEVERED FROM MOUNTING BRACKET AND BEARING DISINTEGRATED. THIS WAS MOST LIKELY CAUSED BY BEARING SEIZING IN THE PULLEY CAUSING THE FORCES FROM THE DRIVE BELT TO SHEAR THE SUPPORT BRACKET. RECOMMEND BELT REMOVAL AND INSPECTION OF THE PULLEY BEARING EVERY 1000 HOURS SERVICE.