Will the aux fan unplug and come out of the car? Yes, hidden connector

E28 technical advice asked and given! Troubleshooting, modifications and more.
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Blue Shadow
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Will the aux fan unplug and come out of the car? Yes, hidden connector

Post by Blue Shadow »

Is there a connector in line with the aux fan or does it plug into the fuse box?

Be nice to have more access to mount it to a new condenser.

Update, found the connector stuffed onto the corner of the fender-core support looking like the wiring goes into the front fender area.

Had to remove the grille/headlight assembly and pull on some wiring to get it out. Seems mine was well tucked away when built, wiring leaving the front harness folded away from the center of the car and connector stuffed into that corner opening. Wiring continued to the fan as it is supposed to. Could have used all that extra length while effing with getting the condenser in, bracketed and openings for hoses.
Last edited by Blue Shadow on Jun 21, 2022 4:29 PM, edited 1 time in total.
Mike W.
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Re: Will the aux fan unplug and come out of the car?

Post by Mike W. »

Yes, there is a plug. Cable tied to the fan frame IIRC. Might be round, might be flat, but it's definitely there.
MyE24
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Re: Will the aux fan unplug and come out of the car?

Post by MyE24 »

Yes, it will, but I wouldn’t mount it to a new condenser.
I’d get a new, modern Spal fan. Much lighter, more efficient, and better air flow.
The original fan is an antique.
Blue Shadow
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Re: Will the aux fan unplug and come out of the car?

Post by Blue Shadow »

Just want this project done. Have another one to do and will probably step up for that one.

Can always retrofit as needed once this system works.

What size fan? What special considerations? Will it operate on the two-speed arrangement the stock wiring provides? Is it a bunch quieter and deliver more cfm?
MyE24
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Re: Will the aux fan unplug and come out of the car?

Post by MyE24 »

I used the Spal 30102048 16" Curved Blade Pusher Fan, $159, you can look it up on Amazon and see the specs.
Yes, lighter, quieter and more air flow.
Yes, it’s easy to wire it so the stock resistor is used, and 2 speed operation maintained.
Are you using a parallel flow condenser?
Mike W.
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Re: Will the aux fan unplug and come out of the car?

Post by Mike W. »

The two speed is just because it goes thru the resistor. If the new fan draws more, it could be a problem. If amperage is the same or less, just use the existing resistor.

Such a simple system and I don't know why other marques don't use it. Instead they just turn the fan on full blast or off.
gadget73
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Re: Will the aux fan unplug and come out of the car?

Post by gadget73 »

Stock resistor is I think 0.5 or 0.6 ohms, not sure the wattage but the BMW replacement is 85 watts in a completely different form factor. Mine got destroyed when I ran over a hunk of plastic wrap from someone's case of water bottles and it wound up in the fan and broke the resistor. My replacement was a no-name 100 watt 0.5 ohm part for about half the price of a functionally identical thing from BMW, I just had to solder some wire pigtails on. Unfortunately the replacement resistors don't mount to the original tab like the old one does so I had to make a bracket for the resistor to attach to and bend it so it sat in the air stream to cool it. Probably have to do something similar if using a different fan since it won't have provisions for the stock resistor. I suppose you could remote mount it, but it would need a fairly substantial heat sink if not in the air stream.


other makers do use multi-speed fans but some do it in different ways. Some have the resistor, others use a two speed fan. In modern times they use a solid state controller that can do infinite speeds and slow ramp-up.
Mike W.
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Re: Will the aux fan unplug and come out of the car?

Post by Mike W. »

Correct, original is .6 ohms. There are two different original parts, one is an open ceramic resistor and the other is a enclosed, finned resistor. The ceramic is easier to replace, it just has the terminals that unscrew, the finned one you have to splice.

Image

Image

Starting in the E39 era BMW went to a PWM fan which gives a wide range of variable speeds, however the PWM part is somewhat failure prone meaning the whole assembly has to be replaced even though the fan and motor is still good, and can be used on simpler cars that just power it with 12V like E28s.
Blue Shadow
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Re: Will the aux fan unplug and come out of the car?

Post by Blue Shadow »

Mike W. wrote: Jun 21, 2022 12:41 PM Correct, original is .6 ohms. There are two different original parts, one is an open ceramic resistor and the other is a enclosed, finned resistor. The ceramic is easier to replace, it just has the terminals that unscrew, the finned one you have to splice.
Right now the splice would be easier, I can't get one screw on the ceramic resistor to loosen.

New cheaper one shown, mine has a copper bracket holding it, must be part of the heat management system.
Mike W.
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Re: Will the aux fan unplug and come out of the car? Yes, hidden connector

Post by Mike W. »

Yeah, I didn't think about your location, even here on the west coast they tend to be really tight, back where they use salt I can only imagine. I don't know why you couldn't use the finned type, except you'll have to fab a new way of mounting it. But somehow I don't think that will be a problem for you.
Blue Shadow
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Re: Will the aux fan unplug and come out of the car? Yes, hidden connector

Post by Blue Shadow »

well with the fan out of the car, the other bolt into the resistor was easy enough. Bigger screwdriver and pressure on the table instead of pressure on the engine compartment wherever the fan was placed for that.
gadget73
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Re: Will the aux fan unplug and come out of the car? Yes, hidden connector

Post by gadget73 »

Mine was a ceramic but I couldn't find that as a replacement. Plug that part number in and you get the metal resistor with pigtails for double the price of the same resistor without the wires. I can solder so I went that route.

Plug for mine was right on the side of the fan, wasn't any need to un-wire anything for removal. The fan was seized when I got the car, had to take it all apart and get it free. Unfortunately the plug was mostly melted, so mine is now wired with bullet connectors instead of the nice factory connector.
Blue Shadow
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Re: Will the aux fan unplug and come out of the car? Yes, hidden connector

Post by Blue Shadow »

gadget73 wrote: Jun 22, 2022 7:43 AM so mine is now wired with bullet connectors instead of the nice factory connector.
Don't know how many BMW connectors you have but I have some wiring harnesses here if you need to scavenge for some connectors. We can talk about them, get you what you need.
gadget73
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Re: Will the aux fan unplug and come out of the car? Yes, hidden connector

Post by gadget73 »

basically if its a BMW part, its a BMW connector. Not too worried about it honestly, its perfectly functional as-is and that was my priority. The other end of that circuit used a very goofy Ford relay that apparently was used in 1973 Torinos with a tow package, and 1984 Lincolns with a diesel engine. You can probably guess the availability of that part. I changed it to use a standard Bosch relay that can be had anywhere.
Blue Shadow
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Re: Will the aux fan unplug and come out of the car? Yes, hidden connector

Post by Blue Shadow »

I know how you roll on getting things fixed. There is you need it.

As to the resistor, My ceramic in a copper bracket is attached to the aluminum fan shroud so that is the heat sink if there is an issue of not enough air across the resistor. The copper bracket has 0.6 embossed in it with another few numbers in a different orientation. Got a spare condenser, maybe from an E36 when Tammer ripped the a/c out of his track car, don't recall. But the fan is there with the mounts and resistor. Trash soon enough. Had it for 12 years or so.
gadget73
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Re: Will the aux fan unplug and come out of the car? Yes, hidden connector

Post by gadget73 »

If the fan is bound for the trash I'll be happy to take it as a spare. It can go on the parts shelf next to the NOS mechanical fan.
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