Aux. fan wouldn't shut off on my 1990 300 E even after the engine is shut off. Here is what I did........
1. Finally I disconnected the battery
2. The next morning I put in a new temp. sensor, connected the battery, the aux fan still enganged.
3. Unpluged the plug to the sensor.....it didn't shut it off. Now I'm running the car with the aux. fan off ( I disconnected it at the connector )
What should I look at next?? Anybody with info please reply. Thanks a million.

Regards

Ian

I had the same problem after the temp sensor went bad on the 190e. To stop the fan I found the fan connector near the AC receiver dryer bottle and disconnected it there.

I replace the temp senor, reconnected the Aux fans and the problem went away.

If you are replacing the sensor, be sure to get the one rated for your car. On close inspection the thermo rating is labled in small print on the metal of the sensor.

Haasman

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'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)

Thanks for your reply. Yes, I had disconnected the fan at the connector you mentioned and also replaced the temp sensor but when I connected the battery ( after putting in a new sensor ), the aux fan was still enganged, but what I didn't try doing was starting the engine and then turning it off.

Seems I am having the opposite problem in my thread:
aux fan 300E

Perhaps info on my thread will help you.
Even if a relay is stuck, or the sensor wire has a short, I am surprised that the fan can get power with the ignition off, since mine cannot. I do have an older model, so perhaps it is a different deal.

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1986 300E 5-Speed 240k mi.