This thread is getting very long so I may have missed something here. Please enlighten me.
Does the low speed fan suppose to come on whenever the AC is turned on? Some say it is.
How do I tell if the no low speed issue is the resistor or the fan (high speed is coming on).
If it is the resistor doesn't it burn and open the circuit to fail? If so, how does inserting a resistor in the circuit fix it? Isn't the original resistor still keeping the circuit open? Do you jump it or something?
Help Please!

 

Watch this video, it will help more than 1000 words

http://m.youtube.com/watch?v=N9IikLr8vz8

The fan comes on low for one of two reasons: 1) The AC system is switched on and had reached 8 bar pressure. 2) The coolant in the engine has reached 105 C (221 F), and it will stay on low until the coolant temp drops to 101 C (214 F)
The fan comes on High Speed when 1) AC pressure rises above 18 bar, or 2) The engine coolant has reached 112 C (234 F), and it remains on high speed until the temp drops by 4 C (7 F) at which point it should revert to low speed.

You're right that putting a new resistor in front of an open resistor won't help anything.

Some people are jumping the low speed wire on to the high line, thus the fan will operate at high speed during conditions that only need low speed.

Note the video I referenced is for a 2006, mine is a 2005 and it's the same, but I believe some earlier models were different. I'm pretty sure both high and low relays are in the car on mine, and only the resistor is in the fan. Some earlier ones had one of the relays on the fan too.

I learned that you don't have to remove the whole front end and drain the radiator to access it. It's a little work to get the front bumper off if you're doing it the first time, but from there you can just undo the upper radiator hose (spills only a tiny tiny bit of coolant) and lean the top of the radiator away from the engine. The entire fan assembly will then slide up and right off the radiator.

Edit: by the way, in case it wasn't obvious, keep an eye on the AC condenser lines when moving the radiator around. It's easy to see part is rubber and flexible, and part is metal tubing and we're careful it doesn't bind bend break etc

 

Oh I see, tap the low speed (thin wire) above the open resistor, put in a good resistor, then tap the other side of your new resistor to the high speed (thick wire) so that the current goes around the open resistor to reach the fan

 

I realized the low speed resistor had burned out in my original fan 18 months ago on my 2003 Cooper. After reading through this thread, I decided to go the route of replacing the entire fan assembly rather than using an external resistor. As some of the replacement fans out there were very cheap (<$80), and carries lifetime warranty. I figure that even if it were to fail again, I have the warranty to get a new replacement. So my fan saga begins.

I ordered a Dorman fan assembly with the 5 wires (2 plugs) connection for my pre 03/2003 build Cooper. The fan was installed in Feb of 2013, it worked fine (I never had any overheating issues). The resistor in the original fan corroded and created an open circuit like all the pictures you see in this thread.

In October, my car overheated in a warm fall day. Luckily, it was just a very short drive into an underground parking garage. I took the car to the dealer, they bleed the system and could not find anything else wrong.

The car ran fine during the long and severe winter in the Midwest, the interior was always hotter than normal, I attributed it to a faulty thermostat for the auto A/C unit (although now I think I may know the real issue).

In June of 2014, we finally had a hot day. I ran into some stop-and-go traffic, the A/C quit and the temp gauge went above normal. Thanks to the A/C quitting, it alerted me to the problem and I pulled over. I stopped and restarted the car after it cooled down, and realized the fan had completed quit, both low and high speed. Some diagnostics with a multimeter showed open circuit in the motor. So the motor had failed and I called in for a replacement, I paid shipping, but otherwise the replacement unit was free.

Unit #2 arrived. It worked fine for 3 days, then again, the A/C would quit and the car would begin to overheat. More diagnostic, the low speed fan will come on, but will not stay running for more than 60 seconds. It shuts off (but I still get voltage from the plug for the low speed circuit) after that, and high speed was completely out. Not good. Called again for the third fan.

Third fan arrived. Ran for 6 weeks, then high speed relay get stuck (tapping would not reset it), it stayed running while my car was parked. In three hours, the voltage was down to 8V and it took almost 30 minutes of jump start recharge before the car would start.

Finally I called my parts dealer, instead of getting a 4th fan, they were kind enough to offer a refund for the original fan and I purchased a TYC instead.

Quick observation, these are absolutely different manufacturers, not just different branding on the same product. TYC has plug that matches the original plugs. Both the big and small plugs has mounting tabs on them to click onto the Cooper wiring bracket. Dorman only has mounting tab on the big plug.

TYC is made in Taiwan, Dorman is made in China.

Originally, I had thought I got a lemon from Dorman, but after three fans, I concluded that their fan for the Cooper is just cheaply made. Had I continue claiming warranty, there is no way they could have made any money on my fan. It is a lose-lose for both Dorman and I.

I will keep you all posted on how the TYC works out for me.

 

With the engine at idle and the AC turned on, you should expect the low speed fan to cycle on and off. On my car, about once every 1 to 2 minutes.

 

Per the Bentley manual, and confirmed by my ScanGauge, the fan operates at low speed at 221F, and turns off at 214F. The fan switches to high speed at 234F and remains on high until the coolant temps drops by 7F. Supposedly it also turns on when the AC is on and the AC system pressure reaches 8 bar (114psi)

*In my case the AC compressor died, so even after a new fan, the low speed didn't come on with the AC, as apparently the compressor wasn't developing 114psi
After I installed a new compressor, the low speed fan functioned as designed.


If the resistor is burnt out, current flows to it, but doesn't get to the fan, thus the fan doesn't run on low speed. If your high speed fan runs but not the low, your low speed resistor has died.
The car's computer (BCM?) sends the power to different wires depending on the temp sensed by the water temp sensor.
A replacement resistor allows the power sent by the BCM to reach the fan. The replacement resistor essentially jumps the original resistor.

 

Looks like the Dorman 2-plug is hard to find these days. I know as I asked my Mini tech to find a blown OEM that I can rewire with a Dorman (Detroit Tuned) upgraded resister relay assembly before I install it. The one that is in there now is a Dorman and there was an issue with the plugs when I put it in. Anyway the tech has yet to come through.

I want to have it all rewired and ready to slip in when I do the fan. The picture of the resister assembly install is a bit confusing but will probably be alright when I have everything in front of me. Anyone have a better picture or advice? Or a better plan? I am tired of changing fan assemblies.

///Rich

 

If you care to try the Dorman 2 plugs, Rockauto still has them. They sent me two in the last 2 months as warranty repair. They really came through for me with all my issues with Dorman, for warranty exchanges, I only paid the one way shipping, which is about $7 via their special rate with Fedex. I got two warranty exchanges with them, and finally bought the TYC and they are refunding the original purchase price of my Dorman. I will buy from them again any day.

I don't mind replacing fan every 2-3 years, but 3 fans in 2 months is definitely excessive. Hopefully the TYC will do better.

 

So how did you make out? Is it working?

 

Did you consider the Dorman resister upgrade before you put the TCY in? Did the TCY have the big green, crap, resister?

///Rich

 

No, I did not consider the external resistor route. I have to say for the three Dorman fan I got (they all have the green round resistor), none of them had a failed, or cracked, or rusted resister when I took them off. The longest run being in the car for about 15 months.

The TYC has a similar resistor, but it looks slightly different. Instead of the metal bands, it seems more like wires under the green insulator. But surely not significantly different.

 

I am not talking about an external resister which will not work with our 2-plug fans easily like the one plug simple bridge and you’re done.

I was talking about this assembly to replace the one that comes on the TYC.

Detroit Tuned Gen 1 Fan Relay Kit

It is made by Dorman and looks like the resister is much more robust than that green wire wound one.

Did the motor itself fail on your Dormans?

///Rich

 

Out of the three Dorman fan assemblies I installed, failed and returned, the fan failed on two of them. One was completely shot, open circuit and all. The other will not stay running for more than a minute.

I did not try just the resistor replacement. I thought replacing the entire fan is the simplest route. It may be an OK option if you have a real original MINI fan, but I would not bother if you have a Dorman fan. The rest of the fan is just not robust enough to put a $42 resistor on it.

 

Four years ago when I purchased my 2004 Cooper S, I discovered the resistor was not working after reading about the problem. I fitted one of the external resistors and everything has been working perfectly over the past 60,000 miles. I didn't need to mess with the fans or radiator. Sometimes the best fix is the easiest.

Eric

 

You are right with that. But for us with 2-plug fans, that is not an option. If I had a later R53, I would do it prophylactically just to be sure.

///Rich

 

I was under the impression that the low speed circuit where the resistor is involved is the same in both pre and post 3/2003 production. The changes are the separation of power steering fan to a different fuse, and moving the high speed relay from the fan body to the fuse box (or somewhere external to the fan). If that's the case, I would thought the external resistor would work for both. May be someone can verify this.

 

Since the relay is moved, there is no need for the two plugs so the new fans only have one. That also means you cannot put a bridge resister on the harness but if you want to use an external resister, you have to attach it to the resister itself which is not simply an external bridge and requires removing the fan to do so.

I do believe that the thread confirms this near the beginning. I wish it were otherwise but alas, it is not.

///Rich

 

Anyone had any problems from bypassing that diode or thermistor?

I'm remote mounting a resistor this weekend and was going to reuse that part, but I broke the connector so it's not really doable any more. I'm just going to leave it out for now unless someone has had ill effects...

Actually, the more I think about it, the more I think it must be a thermistor of some kind. If it was to prevent back fed EMF, you would think both the high and low speed would have it, but it is only on the low, presumably to prevent overheating and failure of the resistor, which it apparently doesn't do very well.

 

I did the resistor bypass on the 2-plug. Read more here:
https://www.northamericanmotoring.co...r-surgery.html

I wired a long 12ga wire loop to the bumper cavity under the LH headlight in case I'd opt for an external resistor, but, I'm really liking the coolong of full time high. You may remove both the burnt resistor & that lil diode/thermistor beside it. If the latter fails, you'll have to redo the entire process.
All of my buddies had their resistors bypassed w/o issue. 2plug or even the simpler 1 plug.

 

Hi guys, new member from Australia here. I have been reading your thread on this issue with the low speed fan as I found my 2004 MCS has this issue. I followed the excellent advice from this thread and ordered a resistor from Mouser Electronics in the US and fitted it last night as per the instructions found here. It worked a treat! I have only had my mini for a few months but found this fan to be an issue and went looking for the solution and found it here with you guys. I love these Minis, they are awsum! My first car was 1978 BlackLeyland mini and 30 years later I am back in a mini and loving it! I will be reading your posts on all things Mini to catch up with all the good and the not so good about our amazing little rockets. Cheer Guys. Craig

 

SO, I have an R53.. and i'm currently about to put the bumper back on after rebuilding the supercharger and a list of 20 other things I updated or fixed while i was in there. I remember the past 6 months noticing that even on days when I would casually drive home from work, I would park it and then the fan would kick on for a minute and then cut itself off. Should i even worry about doing any mods or further diagnostic? Hi speed kicks on when the A/C is on or if it's being driven hard... but isnt this normal? Or what should I do? I BELIEVE the low still works but how can I check that? I do hear the fan kicking on and off when the a/c is on intermittently but again, is that a normal thing to happen? Again... R53 03'. THanks guys! I dont want to put the car back together tonight unless I know for a fact i'm okay to just put it back together but I dont want my car overheating and since this seems to be an issue with the early minis... need to ask you guys the pros

 

Hi!

If you turn on the A/C N' You Fan Kicks On & Off
You low Speed is bad.

Because If You Low Speed Was Ok.
Supposedly The Low Speed Kicks First Went
You Turn The A/C After At Minute of before
The Hi Speed Kicks On N' Stays On.

So You Resistor is Burned

Also The Low Speed Came On at 105°F
& The Hi Speed At 112°F
That's is wend You Don't Turn The A/C

So You Don't Have Fan until Get That Hot 112°F

 

Ahhh... so you recommend just getting the external gold resistor for $15 and wiring it up?

 

Yes That's Correct!

 

Are there any u tubes on the replacement of the blower motor and the final control unit resistor? AL.