1997 BMW 528 AUX FAN

Tiny
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  • 1997 BMW 528
Engine Cooling problem
1997 BMW 528 6 cyl Two Wheel Drive Automatic

car over heats when stopped in traffic. Clutch fan is working fine but Aux fan doesn't come on. I have check all fuses an verified that its not the fan by putting power to the 50 Amp fan fuse.(And it came on) I think it might be the relays or temp sensor, but dont know where these are located or how to test them. I read the temp sensor was on the lower hose but its not. There is a sensor on the side of the radiator with three wires is that the temp sensor?(Passenger side toward engine) Dont know where to go from here.
Sunday, October 17th, 2010 AT 8:03 AM

8 Replies

Tiny
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http://www.realoem.com/bmw/showparts.do?model=DD63&mospid=47585&btnr=17_0105&hg=17&fg=05

Is the #6 part the one you are referring to? The temp switch does tell the fan to turn on, so does the A/C
The circuit diagram is on my desktop, I will pull it up and get it to you straightaway.
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Monday, October 18th, 2010 AT 7:29 AM
Tiny
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Please post with the last 7 of the VIN so that I can send the specific information out.
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Monday, October 18th, 2010 AT 9:28 AM
Tiny
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Vin#WBADD632XVBW09076
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Tuesday, October 19th, 2010 AT 8:59 AM
Tiny
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I dont know what the #6 part is
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Tuesday, October 19th, 2010 AT 9:01 AM
Tiny
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If you right mouse click on the hypertext link, you can open it in another tab. The thing on the side of the radiator is the switch, and if the fan can be proven to work as you have done already, then the next thing to check is to see if the current limiting resistors are open or otherwise broken and not doing anything. Click on this link to show the parts and the exploded view: http://www.realoem.com/bmw/showparts.do?model=DD63&mospid=47585&btnr=64_0832&hg=64&fg=55&hl=16
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Tuesday, October 19th, 2010 AT 4:35 PM
Tiny
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How do I test the switch on the radiator, it has three wires and how do I go about testing limit resistors?
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Wednesday, October 20th, 2010 AT 6:48 AM
Tiny
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Test the resistors with a digital multi meter, home depot has one for <$20. The switch seldom fails, just short two of the contacts together, you will get fan activation from two of the three permutations.
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Wednesday, October 20th, 2010 AT 7:35 AM
Tiny
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Ok so I have replaced the resistors and the switch which both tested to be bad. The problem is the fan still doesn't come on when engine gets hot, it is going in to the red. But when I turn on the AC the fan comes on. What do I have to do next to get this thing to work right. This is really frustrating me.
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Sunday, November 7th, 2010 AT 7:42 AM

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