As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 1795 FLL-CUN, AIR TURNBACK TO FLL DUE TO UNABLE TO PRESSURIZE CABIN OR RUN A/C PACKS AT 23000 FEET. BLEED 1 LEAK ON EICAS WITH NR 2 PACK ALREADY ON MEL. T/S FOUND NR 1 ENG PRECOOLER LEAKING AIR THRU EXHAUST PORT WITH APU BLEED ON. REMOVED AND REPLACED NR 1 PRECOOLER IAW AMM 36-11-08.