Spark

Cooling Fan Description and Operation

Caution: If a fan blade is bent or damaged, do not repair and use the damaged part. Replace a bent or damaged fan assembly with a new fan assembly. Using a fan with a different diameter, pitch, number of blades, or type of blade material may effect the cooling efficiency, performance and engine noise level.

The cooling fans are mounted behind the radiator in the engine compartment. The electric cooling fans increase the flow of air across the radiator fins and across the condenser on air conditioned (A/C) vehicles. This helps to speed cooling when the vehicle is at idle or moving at low speeds.

The engine control module (ECM) commands the fan ON in either high speed, or low speed, depending on cooling requirements. In low speed, the fan is turned ON at a reduced speed. In high speed, the fan is turned ON at full speed. In low speed operation, the ECM provides ground to ECM terminal. The cooling fan relay activates and provides ground to the coils of the cooling fan relay and the cooling fan speed control relay. The cooling fan speed control relay activates and provides power to the coil of the cooling fan high speed relay. The cooling fan high speed relay remains inactive because ECM terminal is not grounded. The cooling fan relay provides power to the engine cooling fan motor through cooling fan terminal and the internal fan resistor. In high speed operation, the ECM provides ground to ECM terminals. The cooling fan high speed relay activates and provides power to the engine cooling fan motor through cooling fan terminal, bypassing the resistors.