As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOTS REPORTED THAT THE NR 1 PACK FAILED IN FLIGHT AND THERE WAS SMOKE IN THE CABIN. MAINTENANCE PERFORMED AN OPS CHECK OF THE LEFT PACK, COULD NOT DUPLICATE DISCREPANCY. TROUBLESHOT FURTHER AND FOUND A PNEUMATIC LINE DISCONNECTED FROM TEST PORT AT LEFT HEAT EXCHANGER. CONNECTED THE LINE TO TEST PORT IAW MM 21-50-03 (4), (B), (3). OPS CHECKED GOOD IAW MM 21-50-00.