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98 E320
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8 Posts
Discussion Starter #1
My aux fans are not turning on and since it is starting to warm up in South Florida, I probably need to get this fixed soon.

I can not seem to get the car in the fan test mode and I am wondering what I am doing wrong. I am

1) Turning the key to position 2 (running position)
2) Holding both Auto buttons for >10 seconds
3) Holding the REST button for 5 seconds.

When I scroll to 20 the value is never 10 and is usually either 3.2 or 21.3, which is nowhere near the 10 it should be.

I have already change the motor for the aux fan, since when I connected 12V to it it didn't work.

Thanks in advance for your help.
 

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98 E320
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8 Posts
Discussion Starter #2
Ok.
I finally got the car into the fan test mode and I hear and see the fans running. But the value for the index of 20 is still 21.3 and not 10.

Does anyone know what this means?
 

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SLK320, MKV Jetta TDI, Mini Cooper S, Lincoln Mark LT
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1,712 Posts
Hold the REST button for 5 sec. Use AUTO to scroll.

10. Blower Control Voltage: 6.0V
11. Emission Sensor: 2.4V
12. Sun Sensor: 4.1V
20. Control Current for Auxiliary Fan: 3.2mA
21. Engine Speed: 44 or 4,400rpm
22. Vehicle Speed: 0 (Car must be moving to show a reading)
23. Terminal 58d: 32 or 32%
24. Battery Voltage: 13.3V

Go to:
MERCEDES-BENZ: A/C Diagnostics & Evaporator Replacement
 

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Registered
98 E320
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8 Posts
Discussion Starter #4
I have read in other posts that the value for #20, referring to the Control Current to the Aux fans has a maximum value of 10 mA.

The value I am receiving is double the value at 21.3 mA.

Could the ECT be causing this? Where is the ECT located? Since I have read that if I unplug it, the fans should run constantly.

Thanks.
 

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1996 210.020
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3,972 Posts
This isn't like the old cars, where the auxiliary fan used a simple switch. The ECT signal comes from the instrument panel.

I don't know why you are seeing >10 on that reading. Perhaps your pushbutton unit is bad.
 
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