As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IN CLIMB N 98 PERCENT LEFT PACK OFF ENG NR 1 BLEED OFF ISOLATION VALVE CLOSED LEFT DUCT PRESSURE 30 PSI. AT CRUISE POWER 87 PERCENT SAME SWITCH POSITIONS LEFT DUCT PRESSURE 20 PSI. REPLACED NR 1 ENGINE PRSOV IAW B737 MM 36 11 04. LK TEST GOOD IAW B737MM 36 11 04 400 801 STEP H. SUBMITTED OPEN PART INFO CURRENTLY ON HOLD.