The low speed fan cycle duty is calculated by the Engine ECU and depends on ambient air temperature. The higher the temp the more it stays on, so cold it cycles, hot it stays on all the time.

 

Chris
Thank you for the information on the cycle duty and all you have done to come up with a fix for people who are having this low speed fan resistor problem.
Steve

 

i just remove the dam ceramic crap and added a jumper wire and done!

 

I just purchased a 2003 MC and i have the 2 connector cooling fan. I have read this thread as well as a bunch others and am still confused. I have plenty of automotive electrical experience, but am still wondering. I have no low or high speed fan. I checked the temp by going into the odometer and the temp shows it gets to 260 and the fan never comes on. i can turn on the ac and the fan will come on. If ac is off i show power on both wires in the wiring harness (big red striped one and smaller red striped one) but fan doesnt come on. I can ground one of the small wires in the smaller connector and the fan will turn on. what exactly does the smaller connector do? I have looked and cannot find a wiring schematic for the 2 connector system anywhere.

Please help!!!!!
PS i dont mind buying a new fan if i am sure this will fix the problem

 

Maybe this helps....

So there are 3 wires actually. ground (has brown in it) and the thin w/red and the thick w/red.

If I recall correctly, the thinner wire goes to the low speed resistor and the thicker goes straight to the fan without passing thru the resistor.

The car calls for the low speed fan and power is applied to the thin wire which passes thru the resistor which lowers the voltage and thus low speed fan.

when A/C on, the car sends power to the thicker wire and the full voltage goes straight to the fan and you get high speed.

I don't know why the car isn't calling for high speed without a/c, but I think it is most likely because of temp. It needs to be pretty hot for the high speed to trigger.

At least that is my take on this.

I followed Chris' fix and it works great. I bypassed the resistor, added the new one in front of my radiator, and spliced into the high speed wire.

All works fine.

 

But that only allows the fan to be high speed all the time. Doesn't the noise make you crazy?

Rich

 

& wait for a blown fuse!

 

... or wait for it to melt the thinner wire of the low speed part of the circuit.
Probably won't happen, but I know even the thicker wire gets pretty hot
when the high speed fan is on for a short while.

 

my 2006 R50 just developed the problem discussed in this thread. My repair shop is 2 hrs away... so my QUESTION IS.... since the high speed fan comes on and stays on... will it damage the fan/car to drive the 2hrs to the shop? Its Interstate driving all the way.... (since sitting still/idling makes the car over heat)

 

If it's not like the interstate between York and Baltimore (practically turns into a parking lot
southbound near the PA/MD border every morning) you should be ok.
Keep an eye on the temp gauge - if it starts creeping above the halfway mark,
you can open the windows and put the heat on -full temp, full fan.
The high speed fan should keep things from getting too hot, anyway.

 

Many mini's have been driven, quite litererly, for years with this issue....
on the highway or when moving the temp will be fine.
when stopped, it will be higher that optium, but the high speed will kick in to prevent overheating or dammage...

 

Thanks ZippyNH and cristo... I make the trip on the 29th on Nov... I'll post the results.

 

Not always true, my heater matrix exploded twice due to this problem...........high speed fan worked.

 

Amazing that this problem is the problem that won't go away. We need a flow chart to diagnose the different symptoms and fixes!

05r50, your statements are correct right up until that A/C thing. The high-speed fan kicks on due to high coolant temp, not the A/C (though the engine-driven A/C compressor may add to engine temp). Actually, the low-speed fan should kick on when the A/C is turned on, OR when the temp hits a pre-determined degree; the high-speed fan kicks on at an even higher pre-determined coolant temp without regard to the A/C being on or not.

MiniMusician, sounds to me that you have the other problem where the high-speed relay is sticking "closed", leaving the high-speed fan circuit running at all times - or, your engine is running too hot all the time and "asking" for the high-temp fan to run. Conversely, the resistor death problem means that the low-speed circuit doesn't work at all, and the engine temp kicks on (and off, and on, and off) the high-speed circuit to cool the engine.

Your symptoms sound different. Doesn't sound like your high-speed fan circuit goes on and off. Does your high-speed fan also stay on (for a long period of time) even after the car is turned off? That symptom could be a sign of a bad resistor, but only if the ambient temperature was hot - and right now in the NE it's pretty cool/cold as I recall.

Before driving all the way to your mechanic, I'd try some simple diagnosis first. Make sure the car is not warmed up yet and A/C is off. Open the bonnet and have someone else start the car. No cooling fan, right? Now have the other person turn on the A/C. Does the low-speed fan come on immediately? Yes = you have a good resistor. No = bad resistor or bad relay in the fuse box.

So let's take the A/C out of the equation. Now turn off the A/C and shut the engine off. Find your two large fan relays in the engine compartment fuse box. They're big, square, green (one dark, one light green in mine) and plugged in down the center row - the high-speed relay is closest to the windshield if I recall correctly. Start the car (A/C off ) and wait for the radiator fan to kick on (you'll probably have to wait until the thermostat opens up and coolant flows in and out of the engine and radiator). Does the low-speed come on first? It's hard to hear with the engine running, but you can shine a flashlight down there or feel the change of vibration on the plastic fan housing. (Watch your fingers - you're a musician...)

If so, wait for the high-speed which should kick on as soon as the coolant temp reaches that higher degree. When the high-speed kicks on it should cool the radiator/engine pretty quickly and cycle off again - either down to low speed or off.

If the low-speed fan doesn't come on first, you may have the resistor problem or your low-speed relay could be bad. Try switching those two relays in the fuse box (I think they're the same/interchangeable). Does this make your low-speed fan kick on? Then your relay's the culprit.

Some if/then scenarios:
if the low-speed comes on first, then the high-speed comes on and stays on high - your low-speed resistor is fine and you probably have a stuck-shut thermostat ($) or stuck (or sticky) relay (cheap). Tap the relay with a screwdriver handle and see if the high-speed fan shuts off; and/or change it out with the other (low-speed) relay to see if anything changes.

if the low-speed doesn't come on at all, but the high-speed does and cycles on and off - then it is probably your low-speed fan resistor as noted in this thread. If you don't want to change out the fan assembly yourself (easy), a mechanic trip would be necessary.

if only the high-speed fan comes on, and stays on constantly - then you may have both a bad low-speed resistor and a stuck high-speed relay and/or stuck thermostat. There are other threads about the high-speed fan staying on (and never going off) after turning the car off (and killing the battery).

If I were in your shoes and I thought the fan (relay or resistor) was the problem, I'd feel comfortable pulling the high-speed fan relay and making the drive without the fan (of course, watching the temp gauge). If the temp rises much above half on the gauge, I'd then pull over and plug the relay back in - but you won't need it for highway driving, especially in the cooler weather. I would be loath to have the fan on high for that length of time.

If, however, your thermostat is stuck closed, I wouldn't drive the car anywhere at all.

I realize that your question was merely about the fan speed on a long drive, so perhaps you're heading to your mechanic regardless, and my coffee-induced diagnoses are moot. But if it is only the fan circuit that worries you, you can save a ton of money (and time, in your case) by DIY.

 

My vote for MiniMusician's symptoms is a problem in the coolant system, most likely a bad thermostat.

Of course, there could be more than one problem occurring simultaneously.

I vote for a coolant problem because on my R50, when the low speed fan was out, even in the hot summer months with A/C on, my MINI would never even pass the halfway point on the temp. gauge. High speed fan would cycle on and off when idling or in traffic, but it was never an overheating risk.

If the temp. gauge is shooting towards hot and the high speed fan is blasting away, the coolant's not doing it's job for some reason or another.

 

correct me if I'm wrong... I should be able to unplug the fan... take a multimeter and ' beep ' the connections between Ground (brown) and the 2 other wires... I read that the high speed fan is wired direct, and the low speed as a resistor in series....IF the resistor is bad, would that not be shown as a Open circuit.. thus having No Beep?

 

I figured what the heck, I'll fill the coolant level to MAX in the reserve tank.... took a spin, and sat in driveway with AC on full blast and coulda swore I heard/felt the low fan kick on and off..... Find it hard to believe it could be something that simple... and of course I dont trust it now. :-/

 

If you're talking about the fan harness plug, then yes. The larger, high-speed wire is 12V direct to the fan motor, and the thinner wire goes through the resistor, then to the fan motor. But I don't know about getting a "beep" using a multi-tester. Getting a response may have to do with settings on the tool. If you check for simple circuit continuity and get none from the thin wire, you do have a bad/open low-speed (resistor) circuit after all.

With the harness unplugged right there, you should also check for power coming from the fuse box/relays. On the chassis harness side, see if there's power coming from the thinner wire when you turn on the A/C. This check being good - "yes" - should confirm that your fan resistor is bad.

But I also agree that you have another problem that is keeping your high-speed fan on all the time. A bad low-speed resistor alone wouldn't make that happen. Is your coolant topped up and fully air-bled? Is the coolant overflow tank full of HOT coolant once the car warms up? If the coolant is topped up but not cooling the engine you either have a bad water (coolant) pump or stuck thermostat. The high engine temp would cause your high-speed fan circuit to stay on all the time. Again, don't drive it very far if this is the case.

 

With the A/C on, the low-speed circuit should stay on all the time, so if the low-speed fan is cycling, your resistor is good but the low-speed relay might be [going] bad. What you may have felt was the compressor itself cycling on and off, seeing as it's not very hot where you are and even with the A/C on high it might not need to stay on 100% of the time to keep the interior as cool as you've set it.

At the risk of further complicating the issue, consider something else that just came to mind: your A/C compressor also cycles on and off depending on how cold you want the interior. IIRC, if the A/C button is pressed inside the car, the low-speed fan is on all the time. However, if I'm wrong, and the low-speed fan circuit is ONLY on when the compressor is compressing, then you would probably have the low-speed fan cycling on and off as well.

Bottom line is, do all of your testing with the A/C set as cold as possible so it constantly stays on and doesn't cycle.

 

It's possible that may have been it. The one time I did have the temp. gauge shoot up quickly was when I had air in the cooling system after a drain/refill. Apparently I hadn't bleed the system sufficiently! After turning the car off, releasing the air via the bleeder screw, and topping the coolant off, everything was fine.

Still, the low speed resistor going bad is a common problem, so I would try to double-check that. It's possible that what you were hearing was the high speed fan cycling on and off with the AC on, which I think is a tell-tale sign that the low speed resistor has failed. At least that's what mine did both times it failed. Next time it fails, I'm going with the resistor/heat sink fix listed on this thread.

 

Great write up even if a little confusing to some

Only joined the sight to look at this thread so i could repair my wifes..

Ah you gotta love Bmw ....They will probably be reading this like they done with the five series forums in the uk and then came out with a fix for the blown turbo's on the diesel 530s.......The vortex ...... basically they chucked away the engine breather filter just as the guys on the forum suggested and fitted a dyson type vortex moulded plastic tube.

Anyways heres who makes these lovely fans for your mini i think

http://www.johnsonelectric.com/johns...n-modules.html

 

Anyone used this kit successfully?

Gen 1 Fan Relay Kit $53.00
If you are having problems with your low speed fan on your first generation MINI, then you need this relay kit to fix the bad diode. This will work for both fan units, the one wire harness, or the two wire harness. You just need to wire it in a bit different than the directions show, see the photo! Very simple and easy to install and saves you from having to buy a whole new fan assembly at a cost of 290.00 dollars! The only way to truly test the fan is with a one of several special programs on the market. You hook up to the car, like a code reader, then you can turn the fan speeds on one at a time to make sure they both work. With out this program, turn the air conditioning on and let the car idle. The fan will run in low speed few a few seconds, every 60 seconds.
Give us a call if you have any questions, but we have installed a few of these kits, and they work great.
More:
http://www.detroittuned.com/shop/?productID=530

 

What's this about fixing the bad diode?
The resistor is the component that fails. The fan should actually work whether
the diode is good or bad. Not even sure what the diode does - possibly blocks
a spike of back emf when the fan shuts off? Somebody tell me if I'm wrong, please.

 

I suspect that the wording is wrong, since it clearly looks to me as if its the resistor that has been replaced with a different style.

 

I believe the wording is incorrect.