As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS NOT DECLARED DUE TO: COCKPIT TEMPERATURE UNCONTROLLABLE, AIR WAS FREEZING AND COULD NOT BE ADJUSTED; AIRCRAFT DIVERTED TO AND LANDED SAFELY AT CUN. REMOVED AND REPLACED CONTROL CABIN ZONE TRIM TEMPERATURE CONTROL VALVE, PER AMM 21-61-21-00-801. OPERATIONAL TEST WAS SATISFACTORY CONTROL CABIN TEMPERATURE IS CONTROLABLE AS DEMAND SELECTION. WARM AND COLD CHECK GOOD.