On my 94 E320 the electric cooling fans do not function. I think they are supposed to come on when the engine coolant is too hot or the A/C is on. Correct? Mine do not work under any circumstance leading to overheating when using the A/C in town. Any suggestions?

thanks, tony

check strip fuse under black cover, located on top of the driver's side strut tower.

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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

If strip fuse is ok, follow path of power cord from the fans to the connector. Connected?

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Selling used Mercedes parts on Ebay...always changing...
cdplayer51 take a look!
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Strip fuse mentioned has nothing to do with the cooling aux fans.
That is Blower/Regulator circuit fuse..

So....You want to address the two different Aux Fan circuits and you are correct on their dual functions.

Here are some test to try:
High Fan circuit verification............
On the thermostat housing, there is a blu, 2 wire sensor. With key ON , unplug that sensor. Fans should come ON high speed.
If NO, then take the top of the relay compartment behind the fuse box and look at the fuse on top of the green relay. That is first suspect.

http://catalog.peachparts.com/RenderScriptTemplate.epc?_cmd=epccat_VehicleAAA&cookieID=2EI1B4MYE2F9026TW2&yearid=1994%40%401994&makeid=MB%40%40MB&modelid=E%2D320%2D001%40%40E+320+Sedan&catid=R%40%40Climate+Control&mode=PA&subcatid=R1075@@A%2FC+ACC+Temp+Sensor&source=www.peachparts.com&clientid=catalog.mercedesshop

http://catalog.peachparts.com/RenderScriptTemplate.epc?_cmd=epccat_VehicleAAA&cookieID=2EI1B4MYE2F904AW4G&yearid=1994%40%401994&makeid=MB%40%40MB&modelid=E%2D320%2D001%40%40E+320+Sedan&catid=P%40%40Body+Electrical&mode=PA&subcatid=P2059@@Auxiliary+Fan+Relay&source=www.peachparts.com&clientid=catalog.mercedesshop


Test 2:
Low Fan circuit verification.......
On the reciever/drier , by radiator,....sensor with the 2 wire 6" pigtail lead..
Slide the plastic covers back off the connectors at the end of the wires and jumper there with a screwdriver..that is Low fans for a/c activation...if NO, same deal , but the Blue relay fuse..if that fuse is bad , replace with a 25 instead of the stock 15..per Benz.........................
If Yes on this test, then suspect is low refrigerant. [ not tripping the sensor b/c of lack of high pressure]

http://catalog.peachparts.com/RenderScriptTemplate.epc?_cmd=epccat_VehicleAAA&cookieID=2EI1B4MYE2F902DEHF&yearid=1994%40%401994&makeid=MB%40%40MB&modelid=E%2D320%2D001%40%40E+320+Sedan&catid=R%40%40Climate+Control&mode=PA&subcatid=R1055@@A%2FC+Temp%2E+Switch&source=www.peachparts.com&clientid=catalog.mercedesshop

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A Dalton

Thanks for the help. I checked both sensors and got no joy from that. So I went to the relays. The fuses on both the green and blue relays were blown. Quick replacement and all is right with the world. Thanks again and I'll be monitoring to see if I can help someone one day.

ciao tony

Change the blu relay one to a 25A............[ low fan]

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A Dalton

Before this thread runs into obscurity, can anyone help me out by taking a picture of the wiring for this circuit? or offer alternative suggestions for wiring these fans?

I kid you not, but the PO installed a section of nomex wire from the cooling fan wires near the drivers headlamp assembly and ran that to a small connector box over the wheel well. Inside the connector was a "jumper wire" and from there, I suppose the wire runs back to the relays under the fuse panel.

The fans have never run while I have had the car. I have always been sure to keep the engine cool while in traffic by keeping the engine revved slightly if I was halted on a hot day and since the blower motor for the AC needs brushes, that has not been adding to the heat load.

I am not opposed to bypassing all the relays and simply direct wiring the fans with a switch under the dash.

Thoughts suggestions and photos are welcome.

And this is also for a 1994 E320 (wagon)

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Brian G.

1994 E320 Wagon with many warts SOLD
1995 E320 Wagon with a beauty mark or two FOR SALE

Have you done the two mentioned test?

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A Dalton

I reread the post and based on your comment, the wiring I was asking about appears to be related to the Blower Regulator as you noted. Looks like I need to tackle that under a seperate thread with pictures of the area in question.

I did not do those tests you detailed above, but will tackle them this evening. I will report the results tonight.

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Brian G.

1994 E320 Wagon with many warts SOLD
1995 E320 Wagon with a beauty mark or two FOR SALE

<>

No, your post states the collong fan circuits.. cooling fans are in front of the radiator.........that is what my posted test pertain to..
Not the blower/Reg circuit. That is a different circuit, Perhaps you saw some of the other blower threads b/c a couple of the answers were blower related as a diagnosis, but they are incorrect.
The original post is for an Aux Fans complaint and the diagnosis and test are for Aux Fan circuits.
However , if you want to check both aux fans and also the blower circuit, let me know and I will give you that test also..

I puchased a 86 300e with a burnt out motor. Replaced the motor with a 1990 motor. All went well. Runs like a top. But over heating is a problem. I found the original electric rad motor was ceased. Cleaned it and lubricatd it and have it running on the test bench, direct wired to a 12V battery. I installed it in the car and it will not run. I would love to have a wiring diagram to see if it is wired right. Thinking of wiring it direct from a switch at the dash. HELP.....

Do the second part of the jumper test at the pigtail switch..

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A Dalton

I am not making my self clear so I took some pictures.

Before them, I did the Tests to check my Aux Fan circuit as you suggested (my aux fans are nonfunctional).

#1 Pulled plug off blue connector at the Thermostat housing - No High Aux Fan. Fuse on 30a relay is ok.

#2 Pulled wires off condensor behind driver's hedlamp assembly - No low Aux fan. Fuse on 15A relay is ok.

Now before I proceed, please look at these pictures. It appears that the PO attempted a repair that tried to fix the Aux fans. Rather than fix them, it appears he crossed the aux fan circiut into the Blower Regulator circuit.

The wire cluster near the headlamp assembly is made up of 4 wires. 2 are brown and 2 are Black/white. They were "patched" to the nomex wire. The nomex wire then ran to the case over the wheel well on the driver's side. I know - What the heck.... Did I mention this was the first benz I bought and did so almost sight unseen. The nomex should have been a sign to me to walk away from the car but I was just uneducated at the time.

So perhaps you understand how I got the Blower regulator and the aux fan circuits together. I just want to make it right and get the car rolling more efficiently.

Feel free to just discuss the Aux fans since that is the topic of the thread. Once I get that resolved, I will deal with the other item.

Thanks for your patience.

Attached Thumbnails

   

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Brian G.

1994 E320 Wagon with many warts SOLD
1995 E320 Wagon with a beauty mark or two FOR SALE

<#2 Pulled wires off condensor behind driver's hedlamp assembly - No low Aux fan. Fuse on 15A relay is ok.
>

Re-read the test #2.
You do not disconnect that sensor..you jumper it at the pigtail wires for low fan.

It looks like he brought down power from F15 blower to work aux fan , but you want to do the test first so I know where you are....

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A Dalton

Arthur,

Found a DIY by Chris W. and pulled the fans off this evening (just before it got too dark). I reassembled everything less the fans due to the need of a commuting car. I figured it would not hurt seeing the fans were not working anyway.

After I got the car running, I tried starting each fan. A direct jumper to each fan resulted in ZIP - nothing. Next, I inspected each motor. On the lower side of each fan housing, there was debris in the form of bug carcasses, plant material and dirt poking out of each motor. obviously sucked in with the cooling air for each motor. I spun each motor tapping lightly on the housings and "stuff started falling out.

After a few minutes of carefully removing the debris, I tried a Jumper and VIOLA! The fans ran! So I suspect the primary problem in my case is the fans were non functional at the motor housing due to sucked in debris fouling the works.

Someone's attempt to "fix" the motors resulted in the damaged wiring that will be repaired this weekend when I reinstall the fans.

Hopefully, I am over the hump on this troubleshooting episode.

I will report on progress when the fans are reinstalled and tthe systems rechecked with operational fans.

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Brian G.

1994 E320 Wagon with many warts SOLD
1995 E320 Wagon with a beauty mark or two FOR SALE