6.7L Cummins Cooling System – Cooling System Diagnostics – Radiator Shutters

Shutters are designed to control airflow across the radiator. If the shutters fail to open when needed, the
engine can run hot. Failure of the shutters to close can resu lt in too much airflow and the engine running cold.
NOTE: Make sure the air temperature sensor is functioning correctly. Check the air-operated shutter
controls. Check for air leaks. Refer to the OEM service manual.