The auxilliary fan on a 1996 S420 does not kick in.
At idle the engine temp rises to 120 degrees but when running the temp is 80 degrees.

I tested the following.

1. I checked the fan separately and it functions in both directions.

2. I replaced temp. sensor top of the engine manifold.

3 Before replacing the temp. sensor I hooked up the car to a SNAP-ON diagnostic tool and it read negative 47 degrees. I did not check the reading after that.

4. I replaced the RELAYs just to be sure.

Is there anything that I am missing?

Thanks.

Neither fan works? No Low speed, no high speed?

Do a search, or just go through the pages in this tech help section...it was just discussed a day or two ago.

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It is a truism that almost any sect, cult, or religion will legislate its creed into law if it acquires the political power to do so. Robert A. Heinlein


09 Jetta TDI
1985 300D

fuse?

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1994|040|W124.036|E500
http://www.mbworld.org/forums/image....ine=1216527951

Thanks for the replies.

The fan does not run at any speed. The fuse is good.

Does anyone know anything about the ESG Control Unit? I heard that this ESG Control Unit controls the auxilliary fan.

I am not sure what its function is. Any ideas?

I may be wrong but I think they run off a temp switch!


Smokie

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95 E420 BigBlue
500E Sway bars
2001 C Class 16 in. Rims
KYB Struts and shocks
Rear spoiler
American Stitches Wheel
Bigred 99 F250 Powerstroke
JVC EXAD Mp3 player
JVC EXAD GPS

Is there a dropping resistor for the fans in that car? In my 500E its behind the drivers headlite and over the years had gotten crusty.

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Jim

1992 500E
2007 CLK63
2003 Audi RS6
2001 Audi allroad

You might have the newer style set-up, where there is no resistor behind the headlight, but some other (not-too-good) gadget between the fans. I should've paid more attention to the posts about that gadget, because then I could tell you its proper name. Either way, I believe the advice given, was to rip it out, and replace it with the spring type resistor (older technology, but it works better/longer).

__________________
It is a truism that almost any sect, cult, or religion will legislate its creed into law if it acquires the political power to do so. Robert A. Heinlein


09 Jetta TDI
1985 300D

Thanks to all who chipped in.

I had to clean the connectors of my Aux Fan control unit and it now works fine.

Since I replaced the relay, temp. sending unit, fuse, etc., I guess everything contributed to the system working and back to normal.

congrats man.

__________________
1994|040|W124.036|E500
http://www.mbworld.org/forums/image....ine=1216527951