Centinel System – Repair Manual – 008-027   Fan Clutch, On-Off

CAUTION  If the fan clutch logic is not set correctly, the ECM will not be able to engage the fan for engine cooling and engine protection. The engine can overheat and damage is possible.

The fan clutches can be controlled by the ECM. The ECM can be programmed for either 12 volts, fan ON or 12 volts, fan OFF. Check the ECM program using INSITE™.

Restrict the air flow to the radiator.

Operate the engine at rated rpm.

If the vehicle is air conditioned, make sure the air conditioning is turned off to prevent continuous operation of the fan. When the coolant temperature reaches 99°C [210°F], check for fan engagement.

NOTE: The temperature given for fan engagement is for fans controlled by the ECM.

NOTE: Fan noise and airflow will increase when the fan clutch engages.

Return the engine to idle and remove the radiator air flow restriction.

The fan clutch must disengage when the coolant temperature drops to 96°C [205°F].

NOTE: The temperature given for fan disengagement is for fans controlled by the ECM.

On Signature, ISX, and QSX engines, the fan clutches can be controlled by the ECM. The ECM is programmed to turn the fan clutch on and off.

Restrict the radiator airflow.

Operate the engine at rated rpm.

If the vehicle is air conditioned, make sure the air conditioning is turned off to prevent continuous operation of the fan. When the coolant temperature reaches 110°C [215°F], check for fan engagement.

NOTE: The temperature given for fan engagement is for fans controlled by the ECM.

NOTE: Fan noise and airflow will increase when the fan clutch engages.

Return the engine to idle and remove the radiator air restriction.

The fan clutch must disengage before the coolant temperature drops to 93°C [200°F]. Cummins Inc. recommends that the fan disengage at 3°C [6°F] below the temperature stamped on the temperature sensor.

NOTE: The temperature given for fan disengagement is for fans controlled by the ECM.