As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE FLIGHT, LEFT PACK WARNING INDICATION ILLUMINATED WITH LOSS OF PRESSURIZATION. PACK REINSTATEMENT PROCEDURES FAILED TO BRING LEFT PACK ON LINE. AIRCRAFT DESCENDED TO FLIGHT LEVEL 11,000 FEET AND PROCEEDED ON COMPLETING SEGMENT LANDING WITHOUT INCIDENT. REPLACED ACM DISCHARGE OVERHEAT SWITCH, OPERATIONAL CHECK OK.