As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED BOTH AIR CONDITIONING PACKS INOPERATIVE. RT PACK WAS PLACARDED PRIOR TO DEPARTURE. EMER DECLARED FLIGHT RETURNED & LANDED WITHOUT INCIDENT. FOUND LT PACK PRESS SENSING LINE LOOSE & DISCONNECTED DURING TROUBLESHOOTING IAW AMM 21-20-00-101. RE-INSTALLED SENSE LINE ON LT PACK & ACCOMPLISHED MPM & MEL IAW 21-01A ON RT PACK. SYS GND CHECKED NORMAL, OPERATION CLOSED.