As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON CLIMBOUT, LEFT AIR CONDITIONING PACK TRIPPED AT FLIGHT LEVEL 050. RESET PACK BUT TRIPPED AGAIN AT FL 250. DIVERTED TO LHR. *S/D* AIRCRAFT DEPARTED CDG WITH RIGHT AIR CYCLE MACHINE INOPERATIVE. AFTER DEPARTURE THE LEFT PACK FAILED AND THE AIRCRAFT DIVERTED TO LHR. FAILURE WAS ISOLATED TO THE LEFT PACK FLOW SENSOR, (P/N 810230-2), WHICH WAS REPLACED.