As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LAX INFLIGHT T1960/28AUG. BOTH AIR CON PACKS WENT TO ZERO FLOW ON CLIMB. ACFT WOULD NOT PRESSURIZE. RETURNED TO LAX AND LANDED WITHOUT INCIDENT. REPLACED BOTH LT AND RT HAND SINGLE ENGINE SECON SEGMENT CLIMB PRESSURE SWITCHES. SYSTEM GROUND CHECKED NORMAL OPS.