As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
COCKPIT TEMPERATURE BECAME EXCESSIVE. TURNED OFF TRIM AIR SWITCH AND TEMPERATURE DROPPED TO 27 DEGREES SUPPLY DUCT TEMP. COULD SELECT HIGHER TEMP BUT NO COOLER THAN 27 DEGREES WAS COMFORTABLE. ALL OTHER TEMP ZONES OPERATED NORMALLY. GROUNDED - YES. REMOVED AND REPLACED CONTROL CABIN ZONE TRIM AIR MOD VALVE PER AMM 21-61-21, OPS CHECK OK.