What was found
(CAN) DURING CRUISE ATTEMPTED TO DESCENT USING THE AUTOPILOT. CREW RECEIVED A MIS-TRIM LIGHT AND TURNED OFF THE AUTOPILOT. EXPERIENCED AN OUT OF TRIM CONDITION. THE ELEVATOR TRIM WOULD NOT ADJUST MANUALLY, TEMPERATURE -19 DEGREES C. MAINTENANCE INSPECTED AND FOUND THE ELEVATOR TRIM TO OPERATE NORMALLY, FREEZING SUSPECTED. THE TABS AND ELEVATORS WERE SUSPECTED AND LUBRICATED IN ACCORDANCE WITH DHC PROCEDURES. OPERATIONAL CHECK PROVED SATISFACTORY. AIRCRAFT WAS RETURNED TO SERVICE.