As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON LANDING CONT CAB TEMP WENT FROM 20-50+ WHILE BEING COMMANDED TO COLD. GROUNDED - YES. ACCOMPLISHED BITE TEST REF B737-800 AMM 21-61-00-700-806-002 NO FAULTS NOTED, REMOVED AND REPLACED CONT CABIN TRIM VALVE REF AMM 21-61-21 DO TO HISTORY.