My cabin fan will not turn on at all now. The last few weeks it has been flaky and will come on after driving awhile but now it is not coming on no matter what. I pulled the glove box and bottom panel on the passenger side and confirmed no voltage to the fan. I traced the wires up to a black box. I don't know where to go from here. I checked all the fuses and they measure good with a meter.

Does anyone have the schematics for the fan?
I have read something about a relay. Where is this relay?

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85 300D Turbo

I had the same problem. I wired up a switch that turns the fan on and off with a rheostat inline to adjust the fan speed. Be sure to use 12 gauge wire and a 25 amp inline fuse. This setup works for me plus all the blend doors work retaining the factory push buttons.

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Regards,
Ian White

1995 E300 Diesel w124 OM606
2014 E550 w212 M278 biturbo

2001 BMW 740i E38 M62 (past)
1981 300SD w126 OM617 (past)

There are two brown wires going to one lead on the fan and other is red/black. Which one did you wire up to the positive? I understand what you did but would rather fix it unless I can't get the parts. But I might be up for this option once I find the problem.

Does anyone have a link to the manual or could email me that part of the manual?

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85 300D Turbo

I have the shop service manual for the W123. PM me if you still need it.

Edit: It's in PDF format, so it's emailable.

Edit 2: It's 411 MB.

On Mercedes, Brown is ground. Green with red tracer or Black with red tracer is positive.

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Regards,
Ian White

1995 E300 Diesel w124 OM606
2014 E550 w212 M278 biturbo

2001 BMW 740i E38 M62 (past)
1981 300SD w126 OM617 (past)

The fan wiring runs to a black box on the top right under the dash. I opened the box and there are a few relays and electronics and everything looks good. Where does this box get a signal from?

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85 300D Turbo

The Automatic Climate Control systems from our W123 era accumulate electrical problems when they get old, specifically the solder joints become brittle over time and come apart. If you're not getting power at the blower power plug and the fuses are all good, and the cables seem to be in good condition, I would check out the ACC unit itself. Reman ones are expensive, but if you're adept with soldering, you can probably fix it. Resolder any joints that look like they are in bad condition and see if that resolves your fan issue.

My 2c,
Daniel

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1982 240D 4spd, 327,000mi

On my 500SEC, when the fan quit operating it had broken one of the soldered joints on the black box connected to the fan motor. Once I re-soldered the few joints in the box, I had no issues with the fan control.
It might be worth taking a careful look in the box before going to the trouble of wiring in a switch to turn the fan on and off.

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-Josh
Testing the cheap Mercedes axiom, one bolt at a time...

If you could figure out a way to host the manual, all of us here at the shop forum would be very appreciative! There are a bunch of free hosting sites around.

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Current cars:
2000 ML55 AMG, 174k miles
2003 C240 T-Modell, 202k miles
1995 S320, 207k Miles

I'm not sure how that'll work though, as the shopforum censors hyperlinks?

http://www.megaupload.com

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1982 240D 4spd, 327,000mi

okay... maybe it just didn't like the link I posted yesterday.
Anyway, I'll start a new thread with the link

Can any more experienced forum members enlighten me of the correct way to do this?

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1982 240D 4spd, 327,000mi

Oh? That link you posted seems to be working?

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Current cars:
2000 ML55 AMG, 174k miles
2003 C240 T-Modell, 202k miles
1995 S320, 207k Miles

Yeah it was just a test.

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1982 240D 4spd, 327,000mi

@Johnathan1

I noticed you have a 77 240D cream/palomino.
Is "palomino" that golden-tan color?

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1982 240D 4spd, 327,000mi

Just got it uploaded and published. I started a new thread in the diesel section

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1982 240D 4spd, 327,000mi