NOTE: Dual control systems are required for automatic radiator shutters and thermatic fans. Shutters must open and fans turn “ON” whenever the intake manifold air temperature rises above its sensor set point. Either condition (high coolant temperature or high intake manifold temperature) must activate the shutters and/or fan.
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 93°C [200°F], check for fan engagement.
NOTE: Fan noise and air flow increase when the fan clutch engages.
The fan clutch must disengage before the coolant temperature drops to 90°C [194°F]. Cummins Inc, recommends the fan disengage at 3°C [6°F] below the temperature stamped on the fan temperature sensor.
If the fan does not operate within the temperature range indicated in the Thermal Control Settings Chart as illustrated, the fan clutch and controls must be checked. Refer to the OEM service manual.
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