As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING FLIGHT, THE CREW REPORTED BOTH LT AND RT PACKS WHERE INOPERATIVE. AFTER DISCUSSING THE SITUATION WITH MECHANIC AND DISPATCH THE PACK WERE STILL INOPERATIVE. THE DISPATCHER DETERMINED THAT AC WOULD HAVE TO MAKE A FUEL STOP TO MAKE IT, SO THE CREW PERFORMED AN AIR-TURN-BACK. MECHANIC WERE UNABLE TO DUPLICATE THE PROBLEM HAS NOT RETURNED. (K)