Radiator Cooling Fan: Description and Operation

DIESEL ENGINE










The electronically controlled viscous fan drive is attached to the fan drive pulley mounted to the engine. The coupling allows the fan to be driven in a normal manner.

The Engine Control Module (ECM) controls the level of engagement of the electronically controlled viscous fan clutch by monitoring coolant temperature, intake manifold temperature, air conditioning pressure and transmission oil temperature. Based on cooling requirements, the ECM sends a signal to the viscous fan clutch to increase or decrease the fan speed.

Fan speed is monitored by the ECM. Fan speeds above or below a calibrated threshold will set a DTC. Circuit concerns will also set fan clutch DTC's.