As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON CLIMBOUT, THE RIGHT PACK WOULD NOT MOVE FROM FULL COLD POSITION. FURTHER INVESTIGATION REVEALED THAT IT HAD CEASED TO FUNCTION. AT FL 250 AIRCRAFT WOULD NOT MAINTAIN PRESSURIZATION. REPLACED RIGTH PACK VALVE PER M 215571. GROUND CHECKS NORMAL.