Hello Guys;
Can someone tell me where to get more information on cooling fan? Someone told me that the fan only goes ON when you're using A/C @ higher temperature reading and not necessary when your temperature gage goes up. What should be the normal reading of temperature within the city at normal traffic? 1997 E420
Thanks

 

Fan (electric) comes on when air is required through radiator to prevent potential over heating.
Its operation is commanded by a combination of AC ON and/or engine water temperature + other possible variables.
Cooling fan speed is also sometimes set at different speeds.
Often AC puts the fan on at Low speed in order to improve the performance of the AC at low road speeds.
High speed for engine cooling.

Temp gauge on dash may be inaccurate. Important thing is that its reading is steady. As a guide only I would expect temp to be circa 90/95C.
Engine coolant starts to boil at say 120C due to antifreeze (differing concentrations) and pressure.

I would expect the fan(s) to be on in city traffic.

Hope this helps.

Stuart

 

Thank you Stuart. I am within the information given on your reply. It's very helpful. In order words, the cooling fan will go on either when the A/C in ON or the engine temperature is high.

 

Correct.

AC may bring the fan on at reduced speed (model dependent etc) so as to prevent annoyance from (under bonnet) fan noise.

Stuart