I ended up using the same size screws, drill bit and tap but my "super high strength" bit ended up snapping in half when drilling hole #3 out of 4, even when using oil to lubricate. I ended up having to grab a hammer and nail it out the other end. 2 Screws seems to allow it to make enough contact for thermal paste to take over heat transfer.

I would get another bit and finish the last hole. 3/4 is better peace of mind than 2/4. Maybe the bit wasnt perfectly perpendicular and that's how it snapped. The aluminum is soft so it should go nice and easy.

I agree with LordOfTheFlies. These resistors get very hot. Making sure it is seated using all available holes, will ensure it does not warp and lift on one edge. I created an aluminum heat sink to mount mine to and then mounted that to the body. So far the resistor has worked great over the last few weeks.

Thank you again to all that helped create and maintain this thread.

Hi,


2006 RHD 5 speed manual, R50.


For those that want (from what I can tell) a proper and conclusive test of stage 1 failure, do this OHM test, takes less than 20 seconds if you have the plug located in the same area as the video and my car.




I now have confirmation that my stage 1 has failed. Can someone please have a look at my pictures and tell me the easiest solution to get stage 1 working again. Hoping I don't have to remove the fan but sure doesn't look like the 'Gate' cover can be removed with the radiator fan in car. Do I have to do the resistor replacement similar to the video, is there a clear DIY on this and link to buy the part and materials?


In the meantime, am I doing massive damage to AC compressor and engine by continuing to drive? I always have my AC on and it seems to be working OK and stage 2 is cycling on and off almost as soon as I start my car even from cold.


Thank you for the feedback and hope that video helps make it easier to diagnose a stage 1 failure.


Did some more reading and I think I am going to just by-pass the resistor and splice stage 1 into stage 2 so that high speed comes on whenever low speed was supposed to come on. Where should I make this splice, I assume somewhere before or close to the fan connection / plug that you do testing on for stage 1 failure?


Anyone been running this splice for a while? Risk of premature fan failure I guess but information suggests it's not a two stage fan so may have minimal effect on how long it lasts and engine / compressor should run cooler with no resistor to fail again.

Spliced the low stage to high stage on the fan side of the wire this morning. Fan kicks in right away when AC is switch on and car is cold. Fan cycles on high speed for a few seconds then shuts-off for about 15 - 20 seconds then on again etc. This was from a cold start with AC on engine not up to temp yet. I am sure this dynamic will change after engine is warm, car is moving, stop n go traffic, etc.


Will post back if my fan dies quickly from running high speed all the time (even though this is was it was doing before).

Have you read this thread from the beginning? Perhaps you should. All the answers you seek are already in this very thread.

Spent hours reading this thread, other threads and watching videos. All good.

If you just did a non resistive splice then yes you will add extra wear to the fan motor. As well as now listening to extra noise and adding load to the alternator/fuel consumption. Best to obtain a high power resistor and splice that between the high low circuits. That gets everything back to normal. Resistor type and value are all described in the thread.

Hi, thank you for your post.


After writing the post you responded to I did further research which led me to just splicing the wires. Reasons:


- It could take a few days at minimum to get the resistor and install correctly and I was nervous that damaged was being done
- The fan is a one speed / one stage. This means that it is designed to speed up and down by the amount of power supplying the fan motor. As per my understanding, you are in fact not saving the alternator or fuel consumption because regardless if the fan is on high speed or low speed the power supplying the wires is the exact same and hence the resistor that takes some of that power and disperses it as heat. This means your alternator and fuel consumption is exactly the same regardless of fan speed as the power supplied is being 'lost' to heat through the resistor.
-Noise is zero issue for me. I am used to fans etc. from cars as I live in a very hot, year round climate where AC compressors and fans, radiator fans, etc. are usually always running. I don't even notice them
-This leads the one negative which is possibly increased fan wear due to always running at a higher speed. I would imagine my fan would have run at high speed more often than not anyway due to the hot climate and the fan is already old so I figured I will just replace the fan and have the two stages back in place whenever the time comes to replace the whole fan unit.
-Finally, there could be positives in terms of engine running a little cooler and AC running a little cooler since the high speed fan is kicking in when the low speed used to. Have zero proof of this but there was some information on that possible effect in the reading I did. Of course, this may also be a negative because engine takes longer to warm-up when cold because fan kicks right into high speed while engine is still warming up, but with the AC always (well 90% of the time) on full blast then odds are the fan would kick in to high speed pretty quick anyway.


So, as you can see I tried to logic through the decision and after pondering for a little decided on the quick, easy, simple and clean approach of performing a proper splice, followed by soldering and sealing of the connection.


:thumbsup:

Your points are valid except for part of the second bullet.
Less current runs along the circuit through the resistor in series with the fan
compared to high speed. Plug in ohms law with an estimate for the fan's resistance to show this.
Me, ... I would consider a direct splice while waiting to get an appropriate resistor without any worry,
but I would also get and put in the resistor when convenient, because I like the design of a two
stage fan better than a one stage fan.

So you are saying the computer tells the car to send less current through the wire for stage 1 and also uses a resistor to further bring the current down so the fan doesn't run as fast as high speed? Hmmmm, well that doesn't make sense either as the fan will be running slower than high speed even without resistor in place and I won't be losing any alternator / power savings over a set-up with the resistor anyway?


No electrical guy here but I assumed the exact same current was being sent through the two wires and the resistor did all the work of reducing the power to the fan to make it run slower. Or, are you saying that because the alternator / power source 'senses' the resistor in place that it will cut back power to that wire because of the resistance?


Again, no electrical guy here but logic tells me that the resistor is doing all the work of reducing the power to the fan and that work is lost to heat which means your alternator or whatever is seeing zero difference in work load.


Looking forward to the explanation of why I am wrong which is more than likely :grin:

The resistor is .33 ohms, and let's say the fan's resistance is about .67 ohms.
13 V through the fan on high draws 20 amps for 260 watts of power.
13 V through the fan + the resistor draws 13 amps with a voltage drop of 8.7 V
across the fan and 4.3 V across the resistor, or 56 watts across the resistor and
113 watts across the fan for 169 watts total.

:grin:
Kind of lost me but I am interested in learning something new for sure. Does it have something to do with the resistor using the same voltage as stage 2 speed but less amps in the process of reducing the voltage to slow the speed down? And I guess since watts = voltage x amps then the wattage / power used will be less. So basically we are talking 7 more amps between high speed and low speed.


Let's have a little fun here :grin:


If I am not mistaken, my R50 has a 110 amp alternator. Let's guesstimate that in my hot climate that the high speed fan would be on at least 50% of the time. So 50% of the time the alternator is running 7 more amps than is needed if it had the low speed option. So my alternator and is getting 'taxed' 3.5/110 = 3.2% more than it should if I had the low speed option. Take in to account the alternator's overall percentage of fuel usage compared to the engine and other components and the fuel difference would be immaterial by running high speed only.


Also, 3.2% more wear and tear on the alternator is pretty low.


Obviously lots of guessing and maybe the fan would run on low speed more than 50% of the time although in my hot climate and AC pumping I would argue it could be more.


Fun fun fun :grin:

Get a textbook on electronics or physics; you can learn the basics fairly quickly.


With the a/c off, the low speed fan will cycle on and off a bit when idling or in heavy
traffic, but not much when driving at normal speeds and the high speed fan will
not come on very much at all.
With the a/c on, the low speed fan runs most of the time and the high speed occasionally.
This all varies a bit with ambient temperature and the type of driving, of course.


The guess of .67 ohms for the fan is partly a simplification (not a simple resistive load)
and partly a guess but is probably pretty close to the mark for this sort of discussion.

Cristo's comments are right on. You use less power with resistor in series. Check out my post from 09-08-2012 on actual current measurements, not calculated values. Fan motors are inductive so a DC resistance measurement of the fan winding's does not tell you the current draw at a given voltage.
As for alternator rating, that is a maximum available current. Not what your car is normally pulling. If you want to know the extra load you have to first determine the baseline. It's all academic but I would guess normal night time all lights on, stereo blasting etc, the alternator may be at half rating. If you run without lights in daytime then less. So that 3.2% is probably low off the mark. Biggest issue of not using the resistor is the greater fan motor wear and having fan motor failure.

Has anyone that did a straight splice 6, 12, 18 months ago report a failed fan? Just curious, thank you.

just a question when the car is up to temp. i noticed that my fan is turned on all the time. is not cycling when the a/c is on. in addition, sometimes even when the a/c is off the fan is still turn on for about 2 or 3 mins before it will turn off. but i do notice (not sure if it happens all the time just rainy last week) when i used my car and it was raining even my a/c is on i can hear that the fan turns on and off. but now no rains yet the fan is turn on again

Hi all, I've been hovering around NAM reading all I can about things on my mini and Am pretty sure my 1st stage fan doesn't work. I have a 2001 mini cooper and the only time my fan spins it sounds like a plane taking off. Reading here I thought it was the resistor so I ordered the heatsink one online and removed the fan. After inspecting the unit the resistor seemed to be fine with no breaks or cracks just some outer corrosion. The multimeter also worked when testing the resistor but checking the diode next to the resistor I found it was dead. No biggie I just bypassed the diode and soldered cables onto the resistor as well encase that gave up some day. After putting everything back in the car and doing the AC test the 1st stage still doesn't work...eventually the 2nd stage fan comes on making a racket. Just to be sure I put my new resistor on the cables I soldered on to the resistor area and still no 1st stage fan. The resistor does get rather hot though so I'm thinking power is definitely getting to it.

I'm now assuming there is a problem with my fan or some point in the wire between the fan and the resistor? Does anyone have any ideas?

Cheers

When checking a diode be sure to use the diode setting on a multimeter as diodes have a breakdown voltage that the multimeter must exceed or it will read as open. On low resistance settings, some multimeters will not meet that minimum voltage. I would be concerned about 'bypassing' the diode. Exactly what do you mean by that? I don't have a schematic of the circuit besides the simple block diagram in the Bently book. But diodes are usually installed in a reverse bias connection across the relay winding to clip off the high reverse voltage induced across the relay winding when the circuit is opened. It saves the circuit driving the relay from damage. Those diodes are usually inside the relay however. Diodes can also be reverse connected across the point contacts of the relay, because when the relay opens there is a high reverse voltage induced by the fan motor windings. This high voltage arcs across the contact points as they open and burns them, now you have a dead relay. This may be the diode you are seeing as diodes are not necessarily included inside the relay across the contacts since most loads are non-inductive, such as lighting. If you remember back when cars used points in the ignition, that is what the 'condenser' (capacitor) did. It absorbed the reverse voltage that produces the point burning arc. When the condenser went bad, your points burned up, and the car conked out.
So the diode plays a critical roll here. So if it is indeed bad, it needs to be replaced.
As to why it still does not run on low speed. You need to do a continuity check (resistance) to chassis ground through the fan starting at the resistor to fan connection and work back all the way to the fan relay at the fuse box. Remember that on your early model the fan relay on the fan is the High speed relay. The low speed relay is on the relay/fuse box assembly. The part about not getting the fan spinning but the tacked on resistor is getting hot is troubling. That means there is current going through the resistor, and a good bit of current. If that current is going through the fan motor but it is not spinning, it would mean the motor is dying and will only start up when given full voltage when power is not going through the resistor. Or maybe the relay contacts are burned and dropping enough voltage so that what is being delivered to the fan through the resistor is not enough to get it spinning.

Thanks for the awesome and comprehensive reply LAHills. As you said I correctly used a multimeter on the diode setting to check whether it was dead. I too was worried about bypassing the diode but I've only seen posts about two other people who have had the same diode die and both of them bypassed without issues it seems. If I knew what diode it was I would have replaced it but for the life of me I couldn't find it out. I bypassed the diode by bridging the connection with some cable soldered to the points. My relays seem to be working fine as I swapped the R3 and R4 around I believe and everything still works fine.

As for the 1st stage fan I think I may have been wrong and it did actually get fixed. It did seem quieter however I had read posts where people said it was silent and they could barely hear it. I've not heard a jet engine sound coming from my engine bay the past couple of days and today for the first time when I parked and turned off the car I heard the fan stop. Usually the 2nd stage fan starts spinning up for a couple of minutes after engine shut off.

I'm in two minds as to whether I should buy a new fan for £100 but I'd much rather save the money.

Am I right in saying the 1st stage fan kind of sounds like a loud PC fan when standing in front of the car and only slightly audible when sitting in the car idle in busy traffic?

Any Idea what diode will replace the broken one? As soon as I find it I'll solder the new one in.

Thanks again.

So it just struck me that you say you bridged the diode. If the diode was configured (wired in) to act as an arc suppressor then the bridge would short the fan power to ground and a fuse should blow. An arc suppression diode would be wired from power to ground, but reverse bias. That is, it would not conduct, then when the circuit is de-energized with the opening of the relay contacts there is a reverse voltage on the fan side of the relay contacts that is when it conducts to ground. So that can't be what it is for, as bridging it would be a short to ground. If you could indulge me, I am now curious about this diode. What does it look like, how big is it, and how is it marked? What does each end wire to. If it is wired in series with the fan it would have to be fairly large as on low speed the surge current into the fan is I think about 20 amps and steady state is 12 amps. I did measurements and posted the info earlier in this thread (9-8-2012). I had my '04 fan apart a couple of years ago and cannot remember what all was in there. Since yours is '01 it may have something mine does not.
Oh, and PS: the low speed fan is indeed fairly quiet. With the engine running it is best to open the hood and look to be sure.

It's wired in parallel to the resistor.
Probably to supress back-emf from the fan motor.

Sorry for the late reply, as cristo said it is a small object wired in series after the resistor.

if you go to page 11 on this thread wolf has posted a picture of the culprit.

https://www.northamericanmotoring.co...lution-11.html

I've also found this thread which may be of use.

https://www.northamericanmotoring.co...tor-issue.html

So how much damage is my bridging likely to cause? Should I bother sourcing a new diode? If so any idea of the specs?

Thanks

That does look like a diode to me but slight chance it is a capacitor. Capacitors can also be used for this purpose. And it appears to be in parallel not series, but can't be sure because of the angle of the photo. Has anyone measured one as being a diode? That is to day, with an open/fried resistor, measure the device and it measures as being a diode. The small size of the device makes it highly unlikely it is in series as I mentioned the constant on state through the resistor is 12.5amps and the inrush at startup is about 20amps. You aren't going to find 30amp diodes that small. And being in series would not serve a function I can think of.
So, it must be for suppressing back emf. But as I said before, the inductance of that resistor has got to be very small and can't make much back emf. And If the resistor you chose for the replacement happens to be non-inductive then the diode is definitely not needed. I have been running the replacement Arcol resistor without a parallel diode since sept 2012 and all is well.
If you wanted to make sure you are reproducing the original circuit, then any 30 volt or so diode with a current rating of 1 or 2 amps should do. Again the inductance of the resistor just isn't very large. The motor would have much more back emf potential but it would have an internal diode. The diode we are looking at here is not connected across the motor, so therefor would not serve that purpose.
As for bridging the diode: Since you say the fan motor is working correctly now, the old resistor and diode must no longer be in the circuit. If the new resistor is in parallel with the old one then bridging the diode would bridge the new resistor as well and the fan would run at full speed. I am guessing that your new resistor is connected to the fan side of the old resistor and the relay side of the old resistor is not connected to the wire going to the fan relay anymore, only the new resistor goes there.

No, parallel.