What was found
D: L PACK HI PRESS ON CLIMB OUT RESULTING IN CABIN ALT CAUTION/WARNING MESSAGE. RAN APPLICABLE QRH AND RETURNED TO FIELD. C: MEL 21-51-1CCAT: C. RT PACK ALREADY DEFERRED.L PACK HIGH PRESS ON CLIMB OUT RESULTING IN CABIN ALT CAUTION/WARNING MESSAGE. RAN APPLICABLE QRH AND RETURNED TO FIELD. (FLIGHT 5514) DEFERRED LT PACK WITH RT PACK ALREADY DEFERRED PER MEL 21-51-1C. MX ACTIONS COMPLIED WITH. PLACARDS INSTALLED