Fan Control

Fan speed is variably controlled by ECC output (power) stage in response to signals from ECC control module. The ECC control module digital control signals vary in length according to required fan speed.

The ECC output stage has an electronic unit which receives the digital control signals and converts them to voltage. If there is no control signal or the fan is disabled, the ECC output stage sends a diagnostic signal to inform the ECC control module of the fault.

If fan speed control lever is set to AUT (automatic) mode, fan speed is influenced by the position of driver's side temperature control dial, driver's side passenger compartment temperature sensor, vehicle speed and engine coolant temperature.

The highest fan speed is selected if driver's side temperature control dial is set to maximum or minimum cooling or heating. The greater the difference between the desired and actual temperatures, as sensed by the driver's side temperature sensor, the higher the fan speed.

As vehicle speed increases, the fan speed will be reduced to maintain a constant airflow throughout the passenger compartment. When heating the passenger compartment after starting a cold engine, the fan speed is gradually increased as engine coolant temperature rises.