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'02 Mini Cooper 1st stage fan not working

55K views 16 replies 7 participants last post by  jetlee3666 
#1 ·
Hi, I have a 02 Mini Cooper recently purchased from a private seller but i have started noticing slight problems with the fan and coolant levels.

It started off with the car blowing cold air in the interior and the coolant levels dropping and the 2nd stage fan staying on for about 10 mins after the car was turned off. My first trip to the mechanic concluded that it was the radiator cap that was not holding the pressure and leaking out of the cap, so got that replaced for around £10. After that the car was running fine for a couple of weeks.

Now the problem has extended to the radiator fans not coming on at all, causing the car to overheat when stationary :confused:

Went back to the mechanic and he goes that it may be an electrical fault as the stage 1 fan is not kicking in, however the 2nd stage works. Suggested that I replace the whole fan unit or wait 2 weeks for the electrician to come in (not a possibility, cant be off-road for 2 weeks!)

So i made a trip to a local breaker who had the correct part available for £20, however before I bought the part I plugged the fan in to see if it would work(externally) but no joy, fans didn't turn and the engine was running hot. The breakers told me that it may well be the fan switch which is mounted to the head, however that would cost a bomb of labor to replace.

Now I'm not sure what to do, I don't want to waste money on repairs that are not necessary, so any advice on this would be greatly appreciated :)
 
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#3 ·
Hi ya

I take it that you have checked the first stage fan relay and fuse there in the engine bay.

There us a good chance the fan resistor has gone, if you do a search for first stage fan resistor you will find loads of ways to rework the system.

I personally bought a 60 ohm resistor and spliced it in :) from bmw p/no 51337071670

Have a read though this link it's a long one but good info it may help

http://www.northamericanmotoring.co...-low-speed-fan-resistor-we-need-solution.html

As for you temp gauge it sounds like you have a problem with your OAT probe you may have a bad connection of some damaged wires, it's behind the front bumper right hand side as you look at the front of the car. You will need to pull the bumper off.


Hope this helps
 
#4 ·
Hi ya

I take it that you have checked the first stage fan relay and fuse there in the engine bay.

There us a good chance the fan resistor has gone, if you do a search for first stage fan resistor you will find loads of ways to rework the system.

I personally bought a 60 ohm resistor and spliced it in :) from bmw p/no 51337071670




Hope this helps
Yeah thats the other thing that crossed my mind, but isnt the resistor mounted on the fan assembly? because I have already tested another fan unit.

Thanks for your reply!
 
#6 ·
UPDATE: I have taken the car to the mechanic who has concluded that it was the fan switch that was faulty. The car now doesn't overheat anymore however the 1st stage fan still doesnt seem to come on!

The mechanic said it needs a whole fan replacement to get 1st stage working again but its fine to drive without it working? Is that true? Opinions please :smile:
 
#7 ·
Hi ya

I take it your mechanic has tested the low speed fan wiring fuses and relay.
Simple and quick to do. Disconcert the black plug for the fan ( left hand chassis leg near bonnet release) there a three wires in the plug one is earth (brown) and the other two are power to the fan one is high speed red/blue 4mm cable) and one is low speed (red/blue 2.5mm cable). Run the car till the first stage is meant to cut in, if you have voltage between earth and low speed fan power your good

If the above is ok and the second stage fan work it's only the resistor

Just replace the resistor it's a very simple job it will take about 1 to 2 hours

You have a few choices as I said above or you can buy these

Splices
10 x Butt Splice blue with heat-shrinkable tubing water-proof: Amazon.co.uk: DIY & Tools

Resistor
BMW MINI ONE COOPER S 1.6 R50 R53 RADIATOR COOLIN FAN RESISTOR SWITCH REPAIR KIT | eBay

Or

Search SiteSearch 17117541092 - 17117541092R - Cooling Fan Resistor Repair Upgrade Kit - ES#2709851

And stay standard ish simple fix :)

Hope this helps
 
#8 ·
I would like to Post a little update.

I went to a more reputable garage who suggested that the Fan Switch was faulty. Got that replaced (cost me £60 altogether) and now only the 2nd Stage fan kicks in. This happens rarely but it seems to have fixed the problem.

It only kicks in if the weather is hot (rarely is in the UK :D ) and I'm stationary for more than 10 minutes. Hasn't caused me any problems and it has been running fine for about 3 months.

My question, does anyone elses Mini do that?
 
#10 ·
It's difficult to say, but it may lead to problems later.

The low speed fan comes on at 105C but the high speed fan does not kick in until the engine gets hotter (112C). The idea is that the low speed fan kicks in to keep the temperature below 105C. The high speed fan should only be needed in exceptional conditions.

Without the low speed fan your engine will be running hotter and the cooling system will be under greater pressure.

Additionally the low speed fan is used when the AC is on to draw air through the AC radiator so this may not be operating optimally.

Personally I would get it fixed to avoid the possibility of it causing problems later on. As marque says it's a relatively easy job to do.
 
#11 · (Edited)
Hi,

I know this is an old thread, but I thought you'd be interested in what I found during testing my 2006 R53 (only has one 3-way connector to fan assembly).

My low-speed fan wasn't working, so I bypassed the resistor.

Bypassing each relay (shorting pins 87 & 30) in turn showed the fan operated in both low-speed and high-speed modes (although of course now at the same speed).

I then ran up the engine to operating temperature and at exactly 105 celcius 221 F) the fan kicked in. I removed the low-speed relay and the fan kept running. Removing the high-speed relay, the fan stopped.

This leads me to think that the low-speed relay wasn't being triggered when it should.

Switching on the air-con resulted in the low-speed fan running as it should, however it kept running even when the aircon was turned off.

Is this normal behaviour?

I know there is a suggestion that the low-speed fan is only meant to come on at 105, but this seems very high; surely it should come on sooner so that the coolant level stays at normal operating temperature.

My above testing shows that the high-speed fan comes on at 105 C which seems a bit more reasonable.

Cheers,

Dave
 
#12 ·
@Dave - diagnosis

Dave, You probably fixed this already but I can think of only one scenario that matches all the behavior you described:
It sounds like the resistor could have shorted (insulation break-down) and also either fuse F5 or the low speed relay failed as well. If this did in fact happen, there would very likely be visual evidence upon inspection of the elements. Ohm readings would be able to confirm a final diagnosis in any case. My US Mini is a 2006 R52 and I found a good wiring diagram on this site: newtis-dot-info (I was prevented from posting a link to the diagram by the mini2.com new user policies).
I think yours is likely the same. Can you please give us an update on how you handled this issue?

Best Regards,
Andrew
 
#13 ·
Dave, You probably fixed this already but I can think of only one scenario that matches all the behavior you described:
It sounds like the resistor could have shorted (insulation break-down) and also either fuse F5 or the low speed relay failed as well. If this did in fact happen, there would very likely be visual evidence upon inspection of the elements. Ohm readings would be able to confirm a final diagnosis in any case. My US Mini is a 2006 R52 and I found a good wiring diagram on this site: newtis-dot-info (I was prevented from posting a link to the diagram by the mini2.com new user policies).
I think yours is likely the same. Can you please give us an update on how you handled this issue?

Best Regards,
Andrew
Hi Andrew,

Sorry, I just realised my original post may have be a bit misleading. I had mentioned I had bypassed the low-speed "relay"; I had meant resistor. I did that by joining the low-speed wire and high-speed wire at the 3-way connector located over the gearbox. This would have had the the effect of having the fan run at full-speed for both low and high-speed conditions.

I wasn't worried about the extra noise, however I thought it strange not to hear the fan come on at all until what I considered quite a high engine temperature.

So I got out my multimeter and removed the low and high-speed fan relays to see what temperature they were being triggered. I found the low-speed fan was set to come on at 105 celcius, and the high-speed at 112 celcius. It seemed strange that the trigger temps were so high.
 
#14 ·
Those are correct temperatures, but with AC on the low speed should come on at a lower value. It's all controlled in DME software anyway. But if you get a chance to record and share the trigger temp for low speed with AC running that would be useful. The only significant drawback I see to bypassing the resistor as you did is extra wear on the fan.
 
#16 ·
EN4, There are multiple control loops for the fan. You have verified the function of the loop that monitors AC via software. But the thermosensor could fail and the fan would still be triggered by AC input to software loop. So I suggest you run the engine with AC off to verify the sensor-based control. Since the same sensor sends input to DME software for both trigger points (105°C & 112°C), it only needs to be verified once (which will be at the lower temperature).

For thermosensor control, I use this diagram for reference on my own vehicle:
a diagram at www DOT newtis DOT info/tisv2/a/en/r52-cooper-s-cab/wiring-functional-info/chassis-suspension/steering-ehps/ehps-steering-assistance/power-steering-pump-fan/u0PE4m4

--Andrew
 
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