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DISCUSSION => Electrical => Topic started by: Birdman16 on August 30, 2008, 12:57:49 PM

Title: Aux. Fan Cooling Problem
Post by: Birdman16 on August 30, 2008, 12:57:49 PM

While driving the other day, I noticed that after a long drive, my aux. cooling fan in front of the radiator quit working.  I have had some hot temps run through the car and didn't notice this until yesterday. It seems to have packed up and left years ago.  I ran some tests and when the curcuit is jumped, the fan works on the high setting but not the low.  When jumped on the low setting, the relay for the fan in the fuse box just clicks.  The resistor it is measuring between 40-50 ohms when tested independant of the curcuit.  Does anyone know what the impediance of the resistor should read, and if it is gone, would the low speed fan not work when the a/c is not turned on?

Title: Aux. Fan Cooling Problem
Post by: quinn11m20 on August 31, 2008, 01:45:39 PM

Yes. At low speed the fan should come on when you turn on the A/C. It could be the heat sink block mounted to the side of the fan. I recently replaced mine because my fan would not turn on when the A/C was on. Replacing it fixed my problem. hope this helps.

Title: Aux. Fan Cooling Problem
Post by: Birdman16 on August 31, 2008, 08:23:56 PM

When you say heat sink block, do you mean the resistor? The resistor is about 3 in long X 1/2 in X 1/2 in with a black wire mounted on each end.

Title: Aux. Fan Cooling Problem
Post by: quinn11m20 on September 01, 2008, 11:37:43 AM

yes. Its ceramic. there should be two leads and then a ground. If I remember right the ground is a brown (turd) color. then one black lead and a red lead.  I replaced it four to five months ago. sorry I couldn't be more informative.

Title: Aux. Fan Cooling Problem
Post by: Birdman16 on September 01, 2008, 05:36:51 PM

Thanks for the help, one will be ordered shortly.:)

Title: Aux. Fan Cooling Problem
Post by: Mike_L on October 18, 2009, 11:28:42 AM

Finally found a thread that matches my problem.

96 318c  and my radiator fan only runs on high.  The relays, I have swaped and same effect, only high.  So the resistor on low speed is burned out and I can't find a replacement.  Anyway the resistor is about 4" x 1/2" in dia. BMW wants you to buy the fan and shroud, the recyclers want to sell the whole fan motor, so where do I get just the resistor or can I build one?  What value ohms am I needing?

Mike In Ky

Title: Aux. Fan Cooling Problem
Post by: quinn11m20 on October 18, 2009, 11:55:03 AM

I bought my resistor from a local german parts garage. Also you can order them through Bav Auto ( http://www.bavauto.com ) I believe they might have it.
All the wires are color coded. But keep in mind, it could be the fan itself. In Florida we use are AC all year round. So it ruled out the fan for me.

Title: Aux. Fan Cooling Problem
Post by: tjts1 on October 18, 2009, 12:26:20 PM

Just jump the resistor.

Title: Aux. Fan Cooling Problem
Post by: DesktopDave on October 18, 2009, 04:21:22 PM

You can cut the resistor out of the harness (on the aux fan frame) & splice the wires together.  I blew a fuse doing that though.  I'd replace the resistor.  I had to drop the bumper to get to it though.  Here's a linky. (http://www.pelicanparts.com/cgi-bin/smart/more_info.cgi?pn=17-40-1-373-177-M14&catalog_description=Resistor%20for%20Auxiliary%20Fan%20%28Bosch%29%2C%20BMW%20E30%203%20Series%2C%20All%20%281984-91%29%2C%20As%20Needed%2C%20Each)  $25 from Pelican, maybe less elsewhere.

Title: Aux. Fan Cooling Problem
Post by: tjts1 on October 19, 2009, 12:34:34 AM

Or you can just use the same size fuse as the high speed.