As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LAX-PHX - CREW UNABLE TO PRESSURIZE CABIN, AIRCRAFT RETURNED TO LAX AND LANDED WITHOUT INCIDENT. CONTRACT MX FOUND AIR CONDITIONING RELAY MODULE LOOSE DUE TO RETAINING FORK BROKEN OFF. MX RESEATED MODULE, INSTALLED NEW RETAINER AND OPERATIONALLY CHECKED SYSTEM. NO FAULTS WERE NOTED. AIRCRAFT RELEASED FOR SERVICE. (W)