Rich,
I just ordered the resistor from Mouser, they showed 1 in stock, but we all know how that usually works. We'll see...

After ordering I had a thought about the relay. First off, I'm no electronics expert, I'm a ME student who hasn't taken Electronics and Magnetism yet, so I only have a basic understanding of electrical theory.

My thought was: the relay works like a light switch in your house, but instead of your hand flipping the switch, the computer flips the switch connecting power across two wires. The relay doesn't care what voltage is going through it, it only connects the two wires together. So on that thought, wouldn't it still work to send 8V to the relay instead of 12V? Since the relay is only a gateway to send power to the fan it shouldn't matter what voltage is sent across the lines. This means that you could still place the resistor upstream from the relay and the same power will get to the fan as if you placed the resistor downstream from the relay. Do we know if the early cars have the built-into-fan relay upstream or downstream? Obviously the relay is upstream from the resistor on the later cars, but I wonder if power is sent through the resistor before it gets to the on-fan relay in the early cars.

I could see where the relay may have an issue with a higher voltage (too much heat or something) but we would be reducing voltage with the resistor, so there should less danger than a standard 12V.

I'm not trying to be argumentative, just thinking out loud and hoping to be corrected by some more electrically savvy folks out there.

Thanks,
Josh

Edit: Ok I thought about it some more, and remembered that if you drop voltage you are increasing amperage. So now more amps are passing through the relay, which could be a problem. I suppose now the question is: can the relay handle the additional amperage generated by the 8V coming from the resistor?

 

Folks....the resistor will work on either desgins if done correctly. The most foolproof method on either car is to remove the rad, then removed the failed compotent, the wire the new one in, mounting it remotely. No need to re-invent the wheel, or permanately modify/dammage the cars wiring harness. Just remember, KISS....Keep it stoopedily simple.
If you want to try some scheme to rewire the fan, etc... Just remember the law of unintentened consquenses....things are interrelated....so just do what you need to do, don't reinvent it.

 

On the newer fans jumping the feeds works fine. It is an elegant and very simple solution that does not damage the harness in any way. No need to remove anything.

On the older fans, it may simply be better to replace the fan as, IMO, if you are going to the effort of taking the fan out, then you might as well put in a new one. And on the older fans the relay also gets flaky with age and they are no longer available separately. That is another reason to think about replacing the unit. And with new fans in the 80-$125 range, I think a new part is the way to go IF you are going to the effort to remove it.

Rich

 

Same thing here. Attaching a picture of the resistor for another reference:

The green coating was not rotted away like that until I touched it. and I could see where the coil was broken around the insulated tube.

 

I am pleased to report that my testing was successful. I connected a 100 watt, 0.33 ohm, wire-wound resistor remotely and it worked; i.e., it restored the low-speed function of my fan. My application is a 2004 MCS, with no fan-mounted relay, so keep that in mind. There are three wires in the harness to the fan: a brown, a red/green, and a red/blue. By connecting the resistor directly from the red/green to the red/blue - without cutting any of those wires - I duplicated the function of the now-defunct green ceramic resistor mounted on the fan. No need to cut any wires, or to put the front end in 'service mode,' or to remove the fan assembly (although I did that in order to ascertain what I now know, and my wires are actually pigtailed off the existing ceraminc resistor, which was a pain.) HOWEVER, I was stunned by how hot the new resistor got during my testing, and it is far more substantial than the ceramic one it replaces, so I am certain that heat is the cause of the premature failure of that device. I have not yet determined how best to create a heat-sink for the new resistor, but one is clearly necessary.

As a previous poster advised, if you try this be sure to do it on the fan side of the connector (near the a/c fitting) so that if you screw it up and/or decide later to install a new fan you won't have jeopardized that connection in any way.

Next step is to source the connectors that could then be inserted between the two halves of the existing connector so that the repair could literally be "plug and play." MINI would be well-advised to develop this inhouse and make it available to us over the parts counter.

Stay tuned.

 

That's GREAT news JAB 67! I'm looking to do the same on my '05 MCS. I wonder if this type of connector would work?

http://shop.easternmarine.com/index....categoryID=211

 

Thats the type of connector I used..........

 

I've seen both .33 and .47 ohm resistors used successfully. What would work best for this application? It appears the .33 is closest to OE spec. I assume the .47 would result in lower fan speed and lower heat? (Pardon my complete ignorance on this)

 

I can't say. All I know is that the 0.33 appears to work for me in that the low speed feature has been restored, and it sounds much like what it had sounded like before the OE resistor failed. But I would think that the greater resistance of an 0.47 ohm would generate more heat and less speed.

 

0.33 is best as its nearest to OE, but 0.47 is more easily available and works OK for me.

 

Thanks guys!

 

I gave up on wiring (02 MCS) and instead just replaced the fan assy. Put the car in service mode, easier than I thought, took less then 2 hours from start to finish.

Why was I so worried about it being hard to do?

 

Haha because everyone on the internet makes doing the work sound 10 times harder than it actually is. Just installed my new fan assembly today and recharged the a/c start to finish in 2 hours. Not hard at all.

 

I did just that to a racecar I just rewired....not so much because I worried about the low speed not working, but because that car doesn't need low speed to keep it cool when high will serve both purposes.

 

Well folks... I installed the resistor yesterday and it works. A few things I noted:
1.) I was apprehensive about removing the front bumper and digging into this job. I've owned numerous E30 and E36 BMW's and a job like this would take several hours. I wasn't looking forward to getting to the radiator, for fear that I would have to disassemble the entire car. Looking into a Mini engine bay is not the most inviting scene. I read a few posts on it to prepare myself and went into the job. I was actually relieved to see that everything is really straight forward. No hidden fasteners that require engine removal to get to them. Taking my time and looking for all these bolts, it took me 30 minutes to get the fan out, and only 15 minutes to reinstall everything. It really is a simple job. So that being said, if you have at least the mechanical abilities of a monkey this job couldn't take more than 3 hours.

2.) My solution was a little different than Chris's (see previous posts). I have the on-fan relay so I had to wire a little differently. I removed the fan and shroud, and my resistor looked just like all the other pics you see. The wire wrapping the ceramic cylinder was burned through. I simply cracked the ceramic cylinder and removed it from the wire loops holding it in place. I soldered leads on to these wire loops and mounted the resistor remotely. I bled the coolant system after removing the upper radiator hose and the low-speed fan came to life.

All together it may have taken 1.5 hrs, to do all this. And yes, I could have simply bought a new fan and installed it, but this was about getting around the faulty system. Also, since it only takes 15-20 minutes to get to the fan if I need another I can do it in an hour.

Thanks to everyone who posted helpful information.

Josh

 

@ Josh,

and where did you mount the resistor?
Any chance of a photo of it?

Cheers

Chris

 

Chris,
I temporarily mounted it to the black plastic above the turn signal. There's a flat spot just in front of the wheel well that I put one screw into. Plastic isn't the best thermal conductor so I will mount it to the body just behind the hood latch permanently. Note that since I tapped into the wiring at the original resistor, and its on the passenger's side (US car) I placed the resistor on the passenger's side as well.

I can get a picture, but there's really nothing to see thats different than your install, except the side of the car that the resistor is mounted. I should have taken pics of how I did this, but I didn't think about it until I finished.

Just for reference could you check your car and tell me at what temp your low-speed fan turns on? I just want to check mine against yours.

Thanks again,
Josh

 

Josh,

Very similar to my experience replacing the radiator fan ... a lot easier than it looked. In my case, however, I replaced the whole assembly with a new one, but, soldered pigtails onto the new resistor terminals:


When this one fails, I'll open up the pigtails, route it to the body and install the aircol resistor.

 

Exactly, thats what I did. I soldered my leads onto the silver rings wrapped around the resistor.

Josh

 

.47 should work fine. But if you can get close to .33 +- 5% that would be better so the Voltage and current don't change over the circuit(don't know the minimum voltage for the fan). But what I saw on the wiring diagram the closed relay should give the path of least resistance(no resistor) when closed and when open it will use the resistor as the path. any resistor "would" work because of the path of least resistance, but thats what leads to this problem anyways. You want a resistor capable of handling the heat from the current/voltage.

 

Anyone know of a a source other than Mouser for the resistor? Looks like August before they would have it.

 

I may have purchased the last one they had in stock. They showed one in stock, and I got it two days later.

I think Digikey has some, but you could likely do a search for "Arcol" or "wirewound resistor". Most of those sites have filters you can use to narrow down your search through the millions of resistors available.

I found this one with a quick search, although its not exactly like the one I'm using. Click Here

 

OK, thanks.

 

Ok, I am back. Finally installed my resistor yesterday, as a Father's Day activity. To refresh, I am driving the 2005 convertible S, the second version without the relay in the fan assembly.

I purchased the Mouser 100 watt, 0.33 ohm resistor. I spent a lot of time in deep thought on the mounting location. I did not want to cut and drill and introduce a new corrosion point, or an ugly install, or a new fouling point under the hood. Also note there is nothing stopping you from mounting it on the passenger side, except you have to route and tie off a longer lead.

You should see three photos below. I will post more photos in the next message.

I decided to mount my resistor on the wiring harness bracket for the fan. On my car this bracket is easily removed. It shares a bolt with an a/c refrigerant connection, and on my car has an empty wiring harness connection. When attached to the bracket as shown, the resistor fits snugly out of the way, but receives an air current from the fan, and is readily removable by removing the bracket.

Note when experimenting with mounting locations, attach a piece of string or wire to your resistor, so you can retrieve it if you drop it by accident. I dropped a 6mm bolt into this space, and I still do not know if it fell onto the road or is still lodged in the engine cavity somewhere.

An alternate location is available adjacent on my car. There is an unused 6mm threaded mounting lug, probably for another wiring harness. I could have a) drilled a 6mm hole in the edge of the resistor and squeezed a 6mm allen head screw and lock washer in to mount the resistor directly to the car body, or b) made my own bracket from (preferably) light steel angle. However, the resistor body is such that the drilled hole would be too close to the edge and not provide a uniform surface for the allen screw to bear on. I have a milling machine and considered cutting some of the fin away to clear the screw. But also, a single mounting bolt risks loosening under vibration and the resistor rotating in its mounting, possibly fouling something else or shorting against the body. See the photo for a hex head 6mm bolt inserted in the unused mounting hole.

After checking mounting clearances by holding the resistor in the proposed location, I removed the bracket and commenced drilling and tapping two mounting holes. Next photo shows bracket and resistor clamped in vise for drilling. I actually drilled resistor holes first in my drill press, and then drilled matching holes in bracket in vise, but I could have drilled both holes with a hand drill in the vise with care. I selected two screws from my scrap collection according to the taps I had on hand.

The screws actually turned into a frustrating failure. In the next photo you will see that I failed to consider that the screws would obstruct the mounting of the wiring harness. In the process of trying alternative screws/washers, I stripped the threads I had cut in the bracket. The bracket steel is surprisingly soft, softer than the resistor aluminum alloy.

I then turned instead to pop rivets. I drilled out the holes to 3/16 inch, and inserted two 3/16 inch aluminum "short" pop rivets with the head on the wiring harness side. I had to clip the edge of each rivet head to clear the stamping shape of the harness, but if I had mounted the resistor just a fraction of an inch lower, this would not have been necessary. I painted the holes with liquid electrical tape before riveting to minimize galvanic corrosion and rust. The resulting mounting just clears the wiring harness.

See next message.

 

Part 2.

In the next photo you may see the final rivet mounting. Notice I filed the sharp edges of the resistor to avoid future hand scrapes. This was also fortuitous because one corner has only 1/8 inch clearance from the plastic air intake. If you do this I recommend trimming a good chunk from all corners with a hack saw. Saw AWAY from the electrical, lest you slip and slice off the terminals! The resistor is roughly centered on the bracket between the stock mounting holes as shown.

Then I soldered 14 gauge leads to the terminals and insulated with TWO layers of shrink tube, because the terminals have sharp corners and I was afraid one layer would fail. See photo.

The final photo shows everything assembled. The separate leads on each end of the resistor make a neat wiring assembly problematic. I used plastic splice fittings, but really regret it. The resulting splice is bulky and ugly. The high speed wire is 12 gauge and too big for the blue 14-16 gauge splice, so I had to buy an $8 box of splices just to get one yellow big splice. I recommend instead peeling the insulation with a knife, weaving the wire together, soldering, coating with liquid electrical tape, and taping the lot together. That would have been much neater, a sounder joint, and saved me $8!

I quickly tested the whole lot and it appears to function as advertised. I started from cold and immediately turned on the a/c, and the fan started immediately while the temperature gauge was still below 1/4. I checked the leads with a pointy probe and measured 14 volts on the low speed wire, and 9.5 volts on the high speed wire (i.e. downstream of the resistor). That gives a 4.5 volt drop across the resistor, or 13.6 amps, 61 watts. Well within range of the 100 watt resistor, but note this resistor does get hot enough to burn a hand! My main fear is that a long day of city a/c driving will damage the wiring harness plugs. I will monitor this. The only possible resolution is moving the resistor to the alternate body mount location, or switching to a larger ohm value, which will reduced current, reduce heat (watts), and slow the fan. Still a lot better than what, $600 for a new fan at the dealer?

Looking at the fan side, that gives roughly (I know motor impedance is a little different) 9.5sq/R at low speed and 14sq/R at high speed, or roughly a 2:1 power ratio, high to low speed.