As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFT ZONE TEMP LIGHT ILLUMINATED. CABIN INTERIOR TEMPERATURE WENT FULL HOT AND WAS UNCONTROLLABLE. ACFT GROUNDED. PERFORMED PACK/ZONE TEMP BITE TEST, REF 21-62, TASK 801. NR 1 CONTROLLER HAS FAULT ZONE TRIM VALVE, HAS HISTORY. REPLACED AFT CABIN TRIM VALVE IAW AMM 21-61-21-000-801 AND 21-61-21-400-801. ACCOMPLISHED PACK/ZONE TEMP BITE REF MM 21-62, TASK 801. NO FAULTS NOTED.