Hello all,

This is my first post to the forum. I wanted to say thanks to all of you for posting all this useful data, which surely saved me time and money when my R50's low-speed engine cooling fan (LSECF) recently conked out. Not being aware of the fan speed test, I was ready to march down the fruitless path of fiddling with the AC refrigerant until I found this thread. So, thanks again.

Special thanks to Chris for puzzling out the resistor specs. I ordered my replacement from Mouser, as suggested by others on the board, and was pleased to receive it the next day-- they're just up the road from me.

Generally my first post to a web board is a dumb question, but I wanted to make this one a little different: a (hopefully not too dumb) suggestion.

There's been some discussion on this thread of where to mount the resistor, because as we all know, there is very little room under the hood of a Mini. (How they got a supercharger in the S is still a mystery to me.) I found a solution that I think works well.

The key considerations in mounting the resistor are heat removal (i.e. through a heat sink and ideally some airflow), ease of access, and of course not interfering with other underhood components or the closing of the hood panel. Additionally, because I was leery of making an irreversible modification to my car, I wanted an option that did not require drilling or cutting.

In the pictures, you can see that I have mounted the resistor behind the bumper, forward and to the left (US driver's) side of the radiator. I fabricated a bracket from a 6" length of 2"x1/8" aluminum strap, bought at the local hardware store. Two notches on the strap fit over the bumper mount studs, which are 13mm studs approx 5" apart. This leaves enough room between the mounts for the resistor, which can be neatly centered on the bracket. I drilled and tapped four holes for the resistor mount for small brass screws, also from the hardware store. I used some silicon goo from the computer store for heat transfer-- a bit too much, actually, as a little bit goes a long way! The screws were just slightly too long, and stuck through the bracket in such a way that they might foul the bumper mount, but a quick pass with the grinder took care of that.

Having mounted the resistor to the bracket, I soldered on two approx 18" leads of 12ga wire. (I should also have painted the soldered connections with liquid tape before mounting, but I couldn't find the liquid tape container and didn't want to go another 100-degree day without AC... I'll do that later, with a long, narrow brush.) The resistor and bracket were then mounted by loosening the bumper mounting nuts, sliding the bracket in from the side, and tightening the nuts again. The bottom nut is tough to get to after the resistor is mounted, unless you pull the chin spoiler panel and approach from below.

I then ran the wires through an existing opening in the radiator surround, then across the top of the radiator, parallel to the existing fan wiring. Splicing in the two resistor wires to the two red wires in the fan wiring was then easy. Note, it doesn't matter which resistor wire gets connected to which red wire, and you don't need to cut the LSECF circuit red wire, because if your stock resistor failed then that circuit is already permanently open.

Now, with the new resistor in place, the LSECF fan again works as intended (and thus so does my AC). The bracket is solid enough that the resistor and its connections are not subject to undue vibration. Heat is carried away from the resistor by the aluminum bracket and the large aluminum bumper assembly it is mounted to, and it gets at least a little bit of breeze up there in front of the rad. Best of all, if one day my fan dies of old age and needs to be replaced, then the resistor, bracket, and wiring can come out with the old fan, and there will be no sign that they were ever there, since nothing was drilled or cut and all the wiring is on the fan side of the wiring loom connector.

I hope this (wordy) post helps someone somewhere down the road.

Best,
Vito
2006 Cooper, 55k miles and no worries

 

Vito -

Nice location.... and great write-up and pics!

My question...

You mentioned your A/C wasn't working because the Fan Speed 1 was dead... and upon fixing the resistor to make the Fan operative, the A/C works again. Is that true?

I've always thought and read that the A/C will can go on even if Fan Speed 1 is faulty.

 

me too. I thought if low speed was out, high speed would automatically work every time low speed was called for.

Oh, and NICE JOB!

 

In the case of a failed resistor, high-speed still works when it's supposed to (it has its own circuit). It will cycle on and off depending on engine coolant temp - it's loud, so you'd be able to tell the difference. The low-speed fan circuit being out will have no operational bearing on the A/C "working" or not, you just won't have a fan blowing on the condenser when you need it (when the A/C calls for it).

 

For clarity: when the LSECF resistor fails, the AC will still turn on. However, at low road speeds or when stationary, without the LSECF there is insufficient air movement over the AC condensor, which leads to warm air coming out of your AC vents. This and the rapid cycling of the high speed ECF were the symptoms that led me to this thread and the resistor failure diagnosis.

Others have mentioned the AC aspect of this problem in this thread already... about 150 posts back!

Best,
Vito

 

In my case, the A/C would only work when I had air blowing across the condensor, otherwise I assume the temp got to high and it would shut itself off to protect it. No low speed meant no A/C at idle for me.

 

just ordered my mouser resistor, had to replace PS pump last year and compressor is already starting to make a lot of racket

i didn't even know about this issue w/ the mini, everytime i look on here i find out something else is broken on this car (i just assumed the fan was ridiculously loud for no reason...)

thx for the fix!

05/2003 MCS

 

Hi, Everyone - new member here. A month ago I bought a 2003 Mini S for my daughter. As soon as I finished signing all the papers relieving the used car dealer from all responsibility for repairs, the heater and air conditioner stopped working. All fuses and relays are fine.
After finding this thread, I checked the cooling fan, and found that the resistor had burnt out. Today I put in a new fan unit, and both low and high speeds are working.
Still no heat or air conditioner, though. It's possible that the two problems are totally unrelated. All the controls, visual displays, interior fans, etc., seem to work fine, but the temperature of the airflow is just the ambient air temp, no matter what the setting. The A/C compressor does not engage when the A/C button is pressed, and no heat comes through the system even though the radiator is warm and water temp guage is normal.

Any advice would be appreciated (except "take it to a dealer", which would be a 600 mile round trip).

 

I'd say to just start going through the fuses and relays. Not sure on your model, but mine ('06) has two fuse boxes: one under the hood next to the air intake box, and one inside left kick panel next to the dead pedal.

Or you could get a Scanguage II and read the codes yourself.

 

All fuses and relays checked out fine, but were swapped with others just in case.

I have been looking into various scanners (I need one which will also reset my airbag light). I hadn't heard of the Scangauge II. I'll check it out.

 

Exactly what part number did your buy and how much did it cost exactly and what wires did you splice this into? Did you take a Pic of the Wire Splice? From taking a short read It looks like even though you are new here you have already taken care of Business!

 

A few days ago I posted a message regarding my problems with my Mini's heater and air conditioner. This thread seemed the appropriate place at the time since my low-speed resistor had indeed burned out, but I have since found that my problems were not related to the fan.

The heater failure was simply the control "door" being off its hinge. After snapping it back into place, the heater is working fine.

More interesting is the AC compressor not working. After several wild-goose chases (like power-steering fan issues), I found that the simplest explanation was correct, as usual: the compressor clutch had burned out.

I'll look for an A/C thread to post the details, but the good news is that everything you've heard about having to replace the entire $500 compressor just because the clutch is bad is COMPLETELY WRONG. If you can get a working clutch from a wrecked unit, it's actually fairly easy to swap it out. No need to disturb the freon lines, the clutch is held onto the front of the compressor with one screw and two circlips. I took pictures, and will post them in an A/C thread when I find one.

 

I read all 20 pages on this subject. So I did some testing on my 2006. I have a rockauto fan that I installed about a month ago. I also replaced the temp. sender next to the thermostat. But, my car was overheating in traffic again. I discovered that the fan wouldn't come on without turning on the AC first. I started the car, cold, unplugged and tested the wires. Nothing. Then I turned on the AC. The smaller of the two wires came on first followed a minute later by the larger one. I thought this was odd because the car had only been running for two minutes, not long enough to call for the fan to come on. Then I turned the AC off and retested. Both wires stayed on. I hot wired the fan and it only came on when I touched 12V to the smaller wire, nothing on the larger one. Judging by the info on this topic I would guess that the resistor on my new fan has gone out. But, I thought the larger wire was for high, and the smaller one for low speed.? I hot wired my old fan, and it is the larger wire that still operates the fan, as the small wire goes to the bad resistor. I ordered the Mouser resistor. Any thoughts on why both wires come on and stay on once initiated by the AC, or why my fan only comes on when I hot wire the smaller of the two? Braman Mini dealer in Miami lies.

 

I read all 20 pages on this subject. So I did some testing on my 2006. I have a rockauto fan that I installed about a month ago. I also replaced the temp. sender next to the thermostat. But, my car was overheating in traffic again. I discovered that the fan wouldn't come on without turning on the AC first. I started the car, cold, unplugged and tested the wires. Nothing. Then I turned on the AC. The smaller of the two wires came on first followed a minute later by the larger one. I thought this was odd because the car had only been running for two minutes, not long enough to call for the fan to come on. Then I turned the AC off and retested. Both wires stayed on. I hot wired the fan and it only came on when I touched 12V to the smaller wire, nothing on the larger one. Judging by the info on this topic I would guess that the resistor on my new fan has gone out. But, I thought the larger wire was for high, and the smaller one for low speed.? I hot wired my old fan, and it is the larger wire that still operates the fan, as the small wire goes to the bad resistor. I ordered the Mouser resistor. Any thoughts on why both wires come on and stay on once initiated by the AC, or why my fan only comes on when I hot wire the smaller of the two? Braman Mini dealer in Miami lies.

 

Don't jump the gun on thinking that your new resistor is blown. Sure it's possible, but I don't know how likely that is.

Consider that there are two reasons your fan comes on: engine coolant reaches a certain temp (or two different temps for the two different fan speeds); and when the A/C is turned on. Fan should at least be on low-speed when when A/C is on. Now consider that you have some desired air temp setting inside the car. When starting out, the car wants to reach that temp as soon as possible (you want that too), so the blower kicks on high which probably kicks on the high-speed radiator fan as well - at least mine seems to do this - which is why you're getting 12V through your larger wire "after a minute" or so. Since/if your radiator fan is disconnected while you test > A/C refrigerant isn't cooling/compressing > the inside air isn't getting any cooler > the high-speed fan and blower circuit keep plugging away trying to reach that temperature for you.

If you "hot wire" the thinner wire and you get low-speed fan, then your resistor is functioning. And if that's the case, you should be able to feed 12V to the non-resistor (larger) wire and get high speed. Check your 12V feed wire again.

For overheating in traffic, I would say that something is wrong with your engine temp sensor: sender, circuitry, relay, fuse, wire..? I don't know which and don't know why you changed it out in the first place. But you may have other problems like low coolant or even a blown head gasket. Pulling codes (with a Scanguage II, for instance) would help nail down whatever's not working before you start throwing more parts at it.

 

Filmy, Thank you for your help. I appreciate your understanding of how things are supposed to work. However as fellow Mini owners we know things don't always work the way they're supposed to. Like our fan problems. To clarify, both of the wires, unplugged, stay hot/on, even when I turn the AC back off, only a minute after I turned it on. Remember too, the engine has only been running for 2 or three minutes. The temperature gauge hasn't moved yet. The coolant is still cool. I tried 3 or 4 for times to get the fan to run by wiring it directly to the larger and smaller wires before putting this question out there to this group. It will only run on the small side. The first test that I did, which I omitted from my original post to keep it brief, was, to start the car cold with no AC, and wait for the fan to come on. It never did. The coolant boiled out of the tank and the fan never came on. When I found this forum I realized the AC connection. It was over heating when I was sitting in traffic without the AC on. I have not had any over heating or lost any coolant since I've been driving with the AC on all the time. Also I should mention that I replaced the Thermostat when I replaced the fan and have confirmed that it is working properly. Despite the big wire, little wire puzzle, I believe Chris's Mouser resistor idea will work. But I don't think it is my only problem. Has anyone found the fan relays to be part of the problem?

 

Hey Filmy and others, Sorry about the long delay in a reply from my post #466, but this weekend I finally made it back to the U-Pull salvage yard and found another BMW to rob the low-speed fan resistor off of.
This time it was on a 1990 BMW 525i. The resistor is located on the fan in front of the radiator/condensor (just behind the front bumper) and is located about the 4:00 position on the outer housing. This one has writing which follows:
Power Motion Mfg.
Mexico C9008 AE 049-600-004

I have since retrofit one of my old Mini fan assemblies with the BMW resistor to my Truimph TR8 to improve cooling, and it works great. It comes on low speed when needed, and kicks on high in traffic. In this case, a two-temp radiator switch from a VW Vanagon is controlling the two-speed fan operation. By the way, the Mini fan is still operating perfectly on my early '03 Cooper S.

 

Ok guys, i have 03 i took a shortcut, and snapped the black plastic covering over where the fuse should be, so what i see now is a green and blue box covering, before i procede with taking the rest off, i wanted to know if the resistor is under one of these boxes.

 

I think you may have the "earlier" system, where there are two separate circuits for each fan speed. However...

In mine ('06) and I think in all of them, the fat round green-wrapped resistor (about the size of 1/3 roll of quarters) is mounted in the fan housing itself: as you stand facing the engine, the resistor is recessed in the top left (passenger side) of the plastic fan housing, and it's on the rear-facing side of the housing. I don't know that you can easily see it while it's still in the car.

IOW, I don't think that what you're looking at is the resistor. I think you're talking about looking in the fuse box itself (on the firewall) and you see the small blue and green fan relays ("boxes"?).

 

Uh oh, i think your right that just about saved me!, SO then in that case does anyone wanna pm that happens to live in CT that could say help me out with this fan problem.

 

You have an '03 (like my Artoo) which means that you cannot use an external resister. So, your only choice is which fan to get when you replace the whole assembly. OEM or aftermarket. And who will do the install?

Rich

 

Dude you are absolutely correct; an additional note: with the low speed circuit open, the fan turns on at 112 degrees C and not 105 degrees C (as it would if low speed was working)

When high speed is called for the ECU still maintains the current path for low and high speed at the same time, therefore if the low speed circuit is bad (open resistor) the fan will run slower in high speed because the parallel path (i.e. low speed) is open resulting in a reduction of the total current flowing through the fan motor!

Depending on the ambient temperature and heat load on the A/C system, the slower running fan (in high speed) may cause further dissatisfaction in the performance of the A/C system.

When the fan is running in high speed and the engine coolant temperature (ECT) falls by 5°C, high speed will drop out and low speed remains (since it was always on during high speed anyway)

The fan continues to run in low speed until the ECT drops some more.

Hope this helps!

 

This is new as no one (to my knowledge) has replaced the clutch w/o the compressor. Please update...

 

03 FTW, well i think tyc from rockauto looks good and as far as whos doing it id be fine with anyone doing it.

 

Rich, I have a first week of July build 2003 MCS, I was able to install one of those aftermarket external resistors (ARCOL HS100 R47) as listed on pg.5, works great should last a long time.
Your build date must be an early 2003.