As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMBOUT AT 280KTS/2000FPM AND 23,000FT CABIN STARTED CLIMBING AT 1,000 FPM. TURNED RATE CONTROLLER TO ZERO WITH NO EFFECT. CABIN HORN FOLLOWED, INITIATED EMERGENCY DESCENT TO 10,000FT. REPLACED LT AND RT MIXING VALVES. LT S/N OFF:2278; RT S/N OFF: 2159