As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 821 JFK-SDQ, AIR RETURN TO JFK DUE TO VENT SKIN VALVE FAULT ON TAKEOFF. AIRCRAFT DID NOT PRESSURIZE AFTER LIFT OFF. REMOVED AND REPLACED VALVE SKIN AIR OUTLET (22HQ) PER AMM 21-26-53-04. ACCOMPLISHED OPS TEST OF AEVC SYSTEM - TEST OK.