BMW E36 Blog

Electric Fan Problems On My BMW E36

20th April 2008

Electric Fan Problems On My BMW E36


I’m having 3 problems with the electric fan in my car.

First, I know that the electric fan should have 2 speeds: Low and High. My electric fan does work on the high speed only, I guess that I’m having a problem here. I also noticed yesterday that the temperature gauge moved a little bit towards the one clock instead of the normal 12 clock position when I left the engine running (with the A/C on) and went to grab something. The second problem that I have with the fan is that whenever the fan kicks in, the RPM bounces for like 20 seconds or a little bit more, then it returns to normal.

The third problem happens usually after I reach home and turn my engine off, the electric fan kicks in and keeps working for like 30 or maybe 40 seconds before it stops.

I noticed these problems before (except for the temp. gauge one) but I didn’t pay much attention to it until yesterday when I popped up the hood and decided to trace how the electric fan is supposed to work. The task is simple; there’s a coolant sensor that is placed in the returning hose to the car’s radiator. This sensor is supposed to keep watching the temperature of the coolant and to send a signal whenever the coolant temperature exceeds a certain value (176F, 80 C according to Bentley Manual).

To my surprise, I found that the electric fan power source is not connected to any special part that is connected to the ECM as I previously thought!! Instead, it’s connected to a relay that can connect/disconnect the fan with the battery directly LOL! I have to say that the electrician who used to work on my babe is a stupid one 😀 . The relay of course is controlled by the coolant sensor and whenever the coolant reaches a specific temperature, it will simply give the relay a signal and thus closes the electric fan circuit with the battery which drops the power from the battery because as we all know, the fan consumes a lot of power and thus the RPM starts bouncing because the ECM is trying to compensate for the loss.

So, I’m trying now to figure out how to re-connect my electric fan correctly to the auxiliary fan relay (which I found in the BMW E36 fuse box layout).

Anyone of you guys can help with this? I need to know what are the colors of the wires that are connected to the electric fan and to the coolant temperature sensor. Some pictures may be good too 😉


BMW E36 Blog: The ultimate BMW E36 M3 information source.


Want to receive exciting tips & information about BMW E36 cars? Enter your Email:-



posted in Cooling System, Technical Info, Tips & Tricks, Uncategorized | 5 Comments

25th February 2007

DIY (Do It Yourself) section is added!



I’ve added a new section to my BMW blog. It’s the DIY (Do It Yourself) section. This new section will have more items as I add new technical tips/information to the blog. So it should grow with time. You can see it at the top menu right above this article. Please check it out and let me know what you think.


Wait for more from . . . BMW E36 Blog


Best regards,

Tony Sticks.

Want to receive exciting tips & information about BMW E36 cars? Enter your Email:-



posted in Uncategorized | Comments Off on DIY (Do It Yourself) section is added!