As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FIVE MINUTES AFTER REACHING FL350 NOTICED LARGE SPLIT IN DUCT PRESSURE. LEFT = 15PSI RIGHT = 45PSI. BEGAN RETURN TO HNL. THIRTY MINUTES LATER LT BLEED TRIP OFF LIGHT & WOULD NOT RESET. REMOVED AND REPLACED 390 SENSOR 450 THERMOSTAT HIGH STAGE VALVE HIGH STAGE REGULATOR & PRSOV SENSE LINE. ALL LEAK & OP CHECKS GOOD.