As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON CLIMB OUT AN ADVISORY MSG VIA ACARS PRINTER, THE RT PACK WAS OFF. WE ALSO HAD AN INDICATION OF THE LT TRIP QRH LED TO TURN THE LT PACK OFF. ACFT COULD NOT MAINTAIN PRESSURIZATION. RETURNED IAW LOG PAGES 8010486 & 8010487. R & R RT PACK ACM & FLOW CONTROL SOV, CORRECTED THE FAULT. VERIFIED LT & RT PACKS ARE OPERATIONAL. PRESSURIZED ACFT TO 1P SI. CABIN HELD AFTER CORRECTIVE ACTION. ALL FAULTS EXTINGUISHED. WORK PERFORMED IAW FIM 21-62-00-810-801 & MM 21-51-04.