As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER DEPARTURE, THE WHOLE CREW SMELLED A RUBBER & ELEC BURN TYPE SMELL. THE PILOT ISOLATED THE SMELL TO THE AIR CONDITIONER & TURNED OFF THE AIR CONDITIONER SYS & THE SMELL WENT AWAY. WE CONTINUED THE FLIGHT BACK TO THE BASE WITH NO OTHER INCIDENTS & COMPLETED A NORMAL SHUTDOWN & CALLED THE MECHANIC. IT WAS DISCOVERED THAT THE AIR CONDITIONER CLUTCH WAS LOCKED DOWN & THE BELT WAS CAUSING THE BURNING SMELL. THE MECHANIC CUT THE BELT OFF. MELED THE AIR CONDITIONER & PLACED THE ACFT BACK IN SERVICE.