As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MIA/LGW - FLT 614 - CAPTAIN REPORTED UNABLE TO COOL CABIN AT FL 310 DURING CRUISE. AIRCRAFT RETURNED TO MIA WITHOUT FURTHER INCIDENT. MAINTENANCE FOUND AFT GALLEY PRESSURE REGULATOR VALVE FAILED. REMOVED AND REPLACED PRESSURE REGULATOR VALVE. OPS CHECKED GOOD IAW 21-60-00. AIRCRAFT RETURNED TO SERVICE. (X)