As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FWD CABIN CONTROLLER SPIKED UP TO 55C UNCOMMANDED. IT DID RESPOND TO COOLER TEMP INPUTS. ACFT GROUNDED. FOUND FWD CABIN ZONE TEMP SENSOR FAN NOT RUNNING. THE FAN BEGAN TO RUN WHILE LOWERING THE PSU. REPLACED FWD ZONE CABIN TEMP SENSOR ASSEMBLY DUCT INSTALLATION ALONG WITH ASSOCIATED FAN AND SENSORS IAW AMM 21-61-14. OPS NORMAL IAW AMM 21-61-00. GROUND VERIFICATION ACCOMPLISHED.