As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
EN ROUTE, CREW ENCOUNTERED A PROBLEM WITH THE AUTO PRESSURIZATION CONTROL SYSTEM. CREW ELECTED TO RETURN TO COS. MX INSPECTED AIRCRAFT UPON ARRIVAL IN COS. MX THEN DEFERRED AUTO PRESSURIZATION FUNCTION PER MEL 21-9-1. ON 28 JUNE, 1997 MX CLEARED MEL DEFERRAL BY REPLACING THE CABIN PRESSURIZATION CONTROL PANEL IAW AMM 21-30-00.