Engine fan

Engine Electric Suction Fan (Cooling Fan) Threshold Temperature

Acknowledgement

This DIY document was based on posts by MBWorld member ‘aleksandar1099’, ‘Jakpro1’, and ‘vrus’ and BenzWorld members ‘Saeed Amini’, ‘wallyp’, ‘jnash’ and 'Ex-Fed'

This DIY document refers to both W211 and W220 models and may be relevant to other Mercedes-Benz models.

STAR DAS can be used to adjust the “Correction programming of the electric suction fan for engine or air conditioning”. “The correction is used for shifting the engine temperature dependence of the electric suction fan for engine or air conditioning”. That is adjust the Engine Electric Suction Fan (Cooling Fan) Threshold Temperature.

Summary

By changing the temperature at which the cooling fan on my 2003 W220 S500L comes on to a lower value, I have improved the performance of the car’s air conditioning on hot days. The air coming from the cabin vents now feels sharp (cold) even when the car is idling at traffic lights. Before the adjustment, the cabin became noticeably and uncomfortably warmer after idling for a few minutes.

Note my air conditioner is permanently left on at 22°C or 23°C in automatic mode. In my opinion the ACC now works as M-B intended, that is completely effectively, even in extremely hot climates, and quite unobtrusively, befitting the performance and elegance of an ‘S’ Class.

In the process I discovered a fabulous tool for wirelessly logging data from my car to my Smart Phone and Desktop Computer.

Detailed Engine Coolant Temperature versus time graphs (before and after adjusting the Temperature Correction Value) are shown.

Sample of data results: A Temperature Correction Value of 0°C (M-B Factory Setting) means the Engine Cooling Fan switches on at 97°C and off at 92°C. This can clearly be seen in the sample graph.

Link to BenzWorld Thread and DIY pdf attachment:

http://www.benzworld.org/forums/w220-s-class/1735481-question-about-star-diagnosis.html