As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIR TUN BACK DUE TO CREW NOTICED A FAINT BURNING SMELL, AIR COND FAULT CAS, YELLOW PACK AIR FAIL CAS, AND LOSS OF TEMPERATURE CONTROL. CREW FOLLOWED EMERGENCY CHECKLISTS AND LANDED WITHOUT INCIDENT AT KAFW. REPLACED THE TEMP CONTROL VALVE IAW CL 300 AMM 21-52-33. REPLACED THE AIR CYCLE MACHINE IAW AMM 21-52-13. OPS AND LEAK CHECK OF PACK SYSTEM GOOD.