As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING CLIMB, THE CABIN TEMP OBSERVED TO BE HIGH, THE AIRFLOW WAS LESS THAN NORMAL. CLIMBING 22000 FT AMSL CABIN PRESSURE WARNING CAME ON, DESCENDED AND ACTION IAW SOP, LANDED BACK. C/O CDS FAULT CODE . FOUND FAULT CODE 3001. PACK FLOW CONTROL VALVE ECS OPT C/O IAW FIM 21-60-00-810-803.