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E39 (1997 - 2003)
The BMW 5-Series (E39 chassis) was introduced in the United States as a 1997 model year car and lasted until the 2004 when the E60 chassis was released. The United States saw several variations including the 525i, 528i, 530i and 540i. -- View the E39 Wiki

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  #1  
Old 05-12-2011, 01:18 PM
ccolizzi ccolizzi is offline
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Location: Geneva NY
 
Join Date: May 2011
Posts: 4
Mein Auto: 99 528i
E39 Aux Fan Problem

I have a 99 528i. I am trying to do as much repair work as I can myself. I currently have a problem with the aux fan. It won't shut off. My "guy" told me its the auxiliary fan control module. I'm not sure if he's calling it the right thing or not (he may be trying to make it confusing just so I have him do the work. It's a silver module that sits behind the fan. It has simple connections that I can make myself if I find the right part. I'm sure the front and fan assembly would have to come off but I'm confident I can do the work for less than 430.00. Can anyone help with a part number of what this is called. I'm not a mechanic but I can be force fed information. Thanks in advance for any help.

Last edited by ccolizzi; 05-12-2011 at 01:26 PM.
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  #2  
Old 05-12-2011, 01:31 PM
JimLev JimLev is offline
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Location: MA
 
Join Date: Dec 2003
Posts: 3,617
Mein Auto: 540/6, S60 Volvo, Tribeca
If it like any other or earlier aux fan I have seen, the motor is powered from relays under the pass side cabin air filter, that are in the DME box.
I posted the schematics a few days ago, pretty easy to trouble shoot and fix.
The temp sensor in the side of the radiator has 3 wires that control 2 relays in the DME box. The HVAC is the control for the 3rd speed.
If you can't find the post, (think it had something to do the someone overheating) I'll post the info again.
What engine is in your car, does it have drive by wire throttle? If so you may have a PWM fan like my car (no relay control), there is no silver module behind the fan.

Last edited by JimLev; 05-12-2011 at 01:33 PM.
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  #3  
Old 05-12-2011, 01:36 PM
ccolizzi ccolizzi is offline
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Location: Geneva NY
 
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Mein Auto: 99 528i
From what I understand, it changed from 98 to 99. The 98 has two simple resistors that are somewhat simple to change. The 99 does not (from what I have been told). As soon as I get my car back tonight I plan to post a picture of the part I need. That should help.
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Old 05-12-2011, 02:15 PM
ccolizzi ccolizzi is offline
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Location: Geneva NY
 
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Mein Auto: 99 528i
Ok the more research I do, the more I think my "guy" isn't right. It makes more sense that the temp sensor in the side of the radiator is shot. The fan has been working fine and all of a sudden I get home and it won't shut off. Most people I have spoken to today say its that temp sensor. This looks much easier to replace than anything else it could be. It there a way to know for sure if this is it? If I unhook the sensor will the fan shut off or will it not work anyway if the sensor is diconnected? Thanks again
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Old 05-12-2011, 05:10 PM
JimLev JimLev is offline
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Quote:
Originally Posted by ccolizzi View Post
Ok the more research I do, the more I think my "guy" isn't right. It makes more sense that the temp sensor in the side of the radiator is shot. The fan has been working fine and all of a sudden I get home and it won't shut off. Most people I have spoken to today say its that temp sensor. This looks much easier to replace than anything else it could be. It there a way to know for sure if this is it? If I unhook the sensor will the fan shut off or will it not work anyway if the sensor is diconnected? Thanks again
If you have a temp sensor in the side of the radiator you should have the old style fan with 2 resistors. The sensor controls the relays I spoke about before. As long as a relay isn't stuck the fan should stop when you unplug the sensor.
Here's the schematic for the old style fan with resistors. The notes were for another guy I was helping, they should also help you.
The temp sensor controls the low and high speed operation.
When you turn on the AC it turns on the fan to low speed.
Mid speed is comtrolled bu the AC pressure switch.
Let me know if you need more info.
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