As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MID CABIN REPORTED EXCESSIVELY HOT. FWD AND AFT CAB CONTROLLERS SET TO COLD. FWD AND AFT CABIN COLD, MID CABIN STILL HOT IAW QRH 2.7 TURNED OFF TRIM AIR. TEMP NOW CONTROLLABLE THROUGH OUT. ACFT GROUNDED. COULD NOT DUPLICATE FAULT. PERFORMED ZONE TEMP CONT BITE ON BOTH CONTROLLERS IAW AMM 21-61-00-806-002, NO FAULTS FOUND. R & R AFT PASSENGER CABIN ZONE TRIM VALVE, V145 IAW AMM 21-62-01.