Just wanted to give you guys an update... I redid the heating cycle to check for the second stage fan activation, and I had indeed shut it down 1° too early the other day. so, second stage kicks in at 112°C just like minsanity said it would. I'm going to go ahead with the first stage resistor workaround posted elsewhere in this thread and under search. thanks again for everything, guys!

 

Good thing you've the single plug harness, Joe. Easy fix.

 

Is that the fix where you splice the relay/ resistor kit at the fan harness? I saw a very short post that has a picture showing steps. I'm looking for it again, now. I'm hoping that's what it is, anyway.

*edit*
Splice a new resistor into the fan side harness between the low speed side and the high speed and Bob's your uncle. Thing is, I've never tapped anything ( that's what she said) so I'm really nervous about drilling/tapping into the motor mount. I wonder if that heat sink paste works as an adhesive. Wouldn't that be grand.

*edit #2
Resistors seem to be out of stock everywhere, so I'm thinking that keeping the car cool is better than not, while I wait for someone to sell me a resistor. That being the case, I could leave the resistor out of the "fix" equation and connect the thin, low speed fan side wire, to the thick, high speed fan wire. It would turn on at the low speed temperature setting, but run at high speed when it does. It would be loud, but it should shut off much sooner than the low speed would have if it worked.. It's cooler out these days in Chicago, but it could also be 97° tomorrow, in Chicago. I don't want the wear and tear that running temps up to the high speed setting brings with it. Temporary workaround, for the workaround, for the factory fan failure?

 

I have a spare resistor from mouser (ended up with two by mistake). I could get it to you for $15 (that's what it cost me, shipped). Pm me if u want it.

Sent from my Galaxy Nexus using NAMotoring

 

Don't worry about it, Joe. A fan's purpose is cooling. Having no resistor cools better. By choice, a number of us are running w/o 1 for quite sometime now w/o issues. If the fan dies, a TYC or Dorman are about $80 or less. Worry more about cooling, than the fan's life. You've already extended it by the bypass.

 

The resistor in the fan 1st stage has not just a function of reduce the speed to fan, but to limit the start current. From not spinning the voltage on the motor or EMF is zero at start.

So you will have 12V/0.33 Ohms = 36Amps. So when the fan start spinning then the motor will generate EMF and increasing speed, voltage and the current goes to its nominal value. The magnetic force exerted on the charges in a moving conductor will generate a voltage (a motional emf). So I would say the voltage with resistor will reach ~8V on the motor. 8/12 = 66%, so the speed is reduce 30%.

My opinion is that running without the resistor for prevent the higher currents during the start up of the fan will reduce the life of the fan. And on this case one day in traffic it will be without fan.

 

Maybe that's what the "diode" (or whatever that little thing in parallel to the original resistor) is for* - to prevent spikes of back-emf when the fan turns on or off.



*pure conjecture on my part - I'd love to hear a better theory if anyone has one.

 

Normally a relay coils has a diode in parallel to avoid spikes when you open the relay circuit. I believe you know those joke books that has a battery and one inductor impedance, when you open the book we cut the circuit and inductor generate a 100 of Volt in the hand of the reader.

To be simple the capacitor opposes to voltage variations and the inductor opposes to current variation. So when you open one inductor circuit it will try to oppose to the current variation to keep the same electrical power, if the current goes to zero the inductor will make the voltage increase creating the voltage spike.

On the resistor that can be a zener diode in parallel. The reason I am saying that is because a zener diode will allow flow in the direction it suppose to be, but even though it does have in the direction of flow a threshold of for example 17V, if the voltage gets above it will conduct maintaining the voltage 17V. But in the opposite direction if the voltage gets above the threshold and a common value is 0.65 it will allow the flow.

But I believe you are correct in the function of that element that is avoid peaks of power in the resistor.

But remember the internal resistor is tight sized for its limits, the external we are recommending 100W that is I think 3 times the power of the internal. I believe the internal should be 33W, so there is a piece of mind in the external resistor we are using.

 

I can't dispute the benefits & purpose of the resistor. Majority, if not all 1st gens bust their stock resistors & are left w/ 2nd stage. Running the 1st stage w/o a resistor is literally like running the 2nd stage & milking whatever life is left of the fan. Some just prefer having a cooler A/C & all the benefits of running a cooler engine. Lower coolant pressure, less likely to split the coolant tank, longer service life for all parts affected by running higher temps (think rubber o-rings & plastics). The fan motor itself seems to be pretty solid as not too many have really lost both stages.....but, it shouldn't hurt much to keep a spare TYC/Dorman fan assembly ready in the garage. Just my $.02.

 

Has anyone replaced the burned resistor with URO Parts replacement???

It's available at RockAuto, part #17117541092R... not sure about quality though.

 

Compare with the one from Detroit Tuned.

 

This looks a bit different from the OE, should be an improved version from Dorman:
http://www.ebay.com/itm/170969660469?redirect=mobile

 

so I spliced the low speed wire to the high speed wire and the fan activates at 105°C... and promptly blows the 30 amp fuse in the engine compartment for stage 1. At 112°C, the high speed kicks on without issue. Any thoughts on why this might be?

 

If everything checks out, your case may be similar to post #411 here:
https://www.northamericanmotoring.com...lution-17.html

Puzzled why a few have blown their 30. Everyone I personally know who've done this mod w/o a resistor never had to change their 30amp fuse.

 

I read 411 and it sounds like the solution was replacing it. No mention is made of what amperage, though. I read that on some models, the power steering pump fan is inline with the stage 1 fan. I didn't consider this because I have the later model fan setup (1 harness plug). So, last night after I had blown the second 30amp, I checked the fuse for the ps fan and it was blown. I don't have another 30 at the moment, but I did use the spare for the 5 amp ps fan fuse. I'm going to have to pick up some fuses, put the car on ramps, and inspect the ps fan. I'm wondering why the spliced fan harness results in the fan pulling 50 amps, but maybe the ps fan situation has something to do with it. Question is, do I use a 50 amp fuse now. Not sure what other issues that might cause. I miss the flexi fan on my '76 Camaro.

 

Early models w/ 2plug harness have the PS fan wired to come on w/ the 2nd stage, not the 1st. MINI revised that later so it would come on w/ the 1st stage. You might be on to something there. Your PS fan might be the culprit.

 

The low speed fan was not working on my 04 MCS, so I inserted a resister like many others have described here and now the fan turns on and off at the proper points.

However..... what led me to this fix was the increasing frequency of having the high sped fan come on after I stopped, and this has not changed with the fix of the low speed fan. Even with ambient temps around 60F, the high speed fan comes on a few minutes after I stop.

So, while driving, the water temp oscillates between ~222F and ~212F as the low speed fans turns on and off. When I turn the car off, the temp continues to increase. The low speed doesn't turn on at its trigger point, but the high speed fan does kick in at its proper ~234F and the temp is brought down reasonably quickly.

I happen to have some driving data from much earlier in the car's life and the water temp never quite gets to 200F while driving in the spring, which leads me to believe there is another problem with the cooling system.

The big question then, is what could it possibly be? Poor water circulation due to radiator blockage (corrosion)? air bubble? faulty thermostat?

Any ideas?

Fun fact: before I put thermal paste between my resistors and the aluminum mount, the resistors reached ~235F. After I reinstalled with thermal paste, they stay under 120F.

 

Fascinating. That thermal paste works wonders!

When's the last time you did a thorough flush/clean of the coolant system? Might be a good place to start if it's been a while.

I used Gunk C2124 radiator cleaner the last time I flushed my system and it seemed to clean pretty well. Took forever to flush it out of the system though.

 

It has been almost 2 years since I last replaced the coolant, so I was planning on doing it soon. However, I never feel like I can get all the water out of the system, and I haven't been much impressed with the shops ability to flush it out either - just from looking at the color.

Are there any good tricks to actually "flushing" it all out? The Gunk sounds interesting, but I'd be worried about getting it all out.

 

Not unwarranted. It's tricky getting things flushed out, and I'm not sure I got it all out myself the last time I did mine. I switched from prestone back to BMW coolant and it's starting to turn dark now, probably from the two combining. I'm going to try flushing out again soon.

Pulling the lower radiator hose seems to get less than half the coolant out of the system. Last time, I just kept pulling it, refilling with distilled water, running the engine for a few minutes, and then repeating until the water came out relatively clear. It took a lot of repeats.

Appartently there's a plug on the engine block that will drain more coolant than just pulling the lower radiator hose. I'll give it a try when I do mine again. This how-to mentions it:

http://www.pelicanparts.com/techarti...ant_Change.htm

 

I used a shop vac to create pressure and sucked all the coolant out. I then ran distilled water one gallon at a time and connected the shop vac at various spots to make sure I was sucking the water through the radiator and block. It worked like a charm and I am pretty sure I got most of the coolant based on the amount I had to recycle (I am sure this goes without saying but always dispose of old coolant responsibly).

There is a thread in the how-to section which walks you through the process. Good luck!

 

Interesting. Must be referring to this how-to.

I'm not sure if it gets more out than pulling the lower radiator hose, but its at least worth a shot. I might try using a shop vac on the lower radiator hose after pulling it and draining to see if it can get what's left in the engine block and heater core out that way.

 

That's the one!

I did not only sick water through the expansion tank though but also a gallon through the lower and upper radiator hoses using the tapered shop vac attatchement. I could feel vacuum in the expansion tank even when I had the vac on the upper hose. I did lift the car and removed the shield from underneath. Worked pretty well for me although i do agree there was some coolant left but I don't think very much.

 

Thanks for the advice and links. Looks doable. Just 100x more involved than previous cars. Oh well.

I'm still wondering if that thermostat isn't opening all the way. It'll be next if a good flush doesn't fix things up.

 

The resistor up at the front of the car is actually a RELAY, it may be called a resistor but from what I can tell if you U Tube search for replacing a/c cooling fan stage 4 relay. He does it fairly quickly.
When I look up
The A/C cooling fan relay
& the A/C Blower motor Resistor
They are not the same part. At www.realOEM.com they show the resistor, but no way to install one. That is a question that I think no one knows the answer to.