What was found
WHILE ON-ROUTE TO KMDT WE RECEIVED AN AP PITCH MISTRIM ANNUNCIATION AND ASSOCIATED MASTER CAUTION. IN ACCORDANCE WITH THE CHECKLIST, AUTOPILOT WAS DISCONNECTED AND THE PITCH TRIM WAS COMMANDED MANUALLY NOSE-DOWN. THE TRIM WHEEL HOWEVER FAILED TO ROTATE VIA THE CONTROL WHEEL SPLIT SWITCH. MANUAL ADJUSTMENT OF THE TRIM WHEEL WAS ALSO UNAVAILABLE AS IT WAS FROZEN IN PLACE. LANDED WITHOUT INCIDENT AND WITHOUT HEAVY BRAKING.