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(MCS) Problem: Engine Fan Stays On

160K views 32 replies 28 participants last post by  Byrdman50 
#1 ·
Hey Everyone.

I'm a very recent MCS Owner and i have a bit of a problem.

My engine radiator fan stays on. Not just for 5/10/15 mins.. It stays on constantly no matter what the temp of the engine is.

When i unplug the connector, it obviously turns off. When i plug it back in its back on instantly.

Also, when i disconnect the battery, and connect it back up.. it starts the fan straight back up..

I understand the fan is ECU controlled, and have read on the forums that disconnecting the batterie for 30+ mins should reset it.

Can anyone suggest any fixes for the problem? And roughly how much the part will cost.

Thank you in advanced for any help.

-David :)
 
#2 ·
Update..

Disconnected the battery for an hour, reconnected and as you could of guessed.. fan came straight back on without the car even started.

I understand that after 2003 they changed they way that the radiator fan system works, and at some TLC services they are changing pre-2003 MCS's to the new system.

I still have my TLC book with 1 voucher left, is there any possiblity my local Mini Garage will fix/change the problem part?

-David
 
#19 · (Edited)
Tap



I have an '02 MCS with this problem, currently.

The first three pictures attached are progressively closer views of where to find the box you tap on.
It is indeed well hidden but once I found it, it was the quick fix.

In case that ISN'T the problem, the last 2 pictures are the power source for the fan. You can unclip it, rather than disconnecting your battery, so it won't drain your battery.

I was mildly frustrated that no one had taken the time to put these up.
And if someone HAS put something like these pictures up, I was frustrated that I couldn't FIND them ;)

Hope this is helpful.
 

Attachments

#6 ·
Right, I had the same problem, ended up having to replace the fan unit completely:eek: .

Below are pictures of the part that cause's the problem. You can't buy this part separately, I believe it regulates the speed of the fan.... You can't see this part as its tucked away:mad: :mad:



 
#7 ·
I had the same problem - sharp tap in the centre of the fan cowl (by the above module) sorted it.
The dealer fitted a new assembly & told me the car was ready, when I got there it was in bits they said it didn't cure it. After another day they said the air con system had too much gas in it !!!! never heard of a car gaining gas over the course of a year
 
#8 ·
Prowse said:
Er, just out of interest, what did you nudge?
After unplugging the fan, follow the radiator accross to the left while looking at the fan. When you get the end of the fan, give a little tap with your fist to the radiator.

Plug the fan back in, everything works fine :)

-David
 
#9 ·
Thanks David......this worked a treat, there must be an underlying problem though.....shouldn't have to hit something to get it to work properly....for now it's a quick fix, so i THANK YOU very much.
I do have one qustion for you though.....how did you work out where to tap??:)
Cath
 
#10 ·
this happened to me once on the way to school, it was raining, and I ended up with a dead battery after 3hrs. I had to call the campus police to get a jump start. but that was the only time it happened to me. so I know, where is the plug to the radiator fan?
 
#15 ·
That big green unit controles fan speed 2. You will also find a relay in there. The green thing is just a big resisitor. In the plug you will have a constant power (allows the fan to be opperated with the ignition is off) The other large wire is the switched wire from the fan control relay. The other smaller wire is the signal wire to activate the relay when the eng is switched on. The relay is a 87 and 87a type and commanly fails burning out and causing the fan to run constantly that is why hitting them turns them off. I will dig up a wiring digram for it as iv seen many minis with this problem.
 
#16 ·
Hi Putsy,

I see that you are in Brisbane (like myself).

I have just recently bought a 2006 JCW MCS (50K on the clock).

Do you know anywhere good here to get the mini independently looked at? Want someone to give me some real advice before I run out of warranty (have 3months left).

One question I do have is Radiator fan related.

Basically I can't hear a fan when the car is idling and the AC is off. but when i turn the AC on (and doesn't matter if the car is hot or cold) the Radiator Fan switches on for about 5seconds, then turns off, every 40seconds or so.

Is this normal?

Thanks.

..schneller..
 
#21 ·
It's the fan

I had the same problem - quite common on the blogs from looking.

Every time I turned the car off the fan cut in - over time got louder and lasted for longer.

If it goes on too long it drains the battery so you are right to unplug it ( Mini mechanic showed me how ).

I had to get a new fan fitted - wasn't very happy as I only have 16K on the clock but it's all fine and dandy now.

Expensive to fit as they have to take the whole front of the car off to get at it apparently - not sure if covered on warranty but I had a leaking roof in 3 times on warranty and in the end got a new roof and wasn't charged so I would like to think so. Got a deal on this so don't know what the dealer would charge sorry :hmph:
 
#24 ·
Hi Guys,
I'm from Sydney Australia. Had the same problem for about 3 month or more. Finally my Second Service time came up and was told that the FAN HOUSING needs to be replaced which costed me AUD$700+. I was not happy.
Hello, I've actually had this issue on my 2003 MCS, and have been trying to find a solution.

First off there are two issues:
1.) The high-speed relay sticking
2.) The low-speed resistor failing

As you've read, on the early cars (2002 through early 2003) the high-speed relay is on the fan housing near the resistor that fails. A quick tap with a screw driver will usually "unstick" the relay and allow the fan to shut off. For cars built after 2003 this relay should be in the fuse block and not on the fan (at least for U.S. cars). Unfortunately the Mini D and One are not sold here in the states so I cant speak for those models (Cooper, CooperS, and Clubman is all we get). That being said I cant imagine there being a large difference in the fan wiring between the models.

For you guys with a relay on the fan housing, your only choice is to replace the entire fan housing if you get tired of tapping on the relay. To my knowledge this relay is not sold separately (at least I cant find one). If you have a late-model Mini you should be able to replace the cube-shape relay in the fuse block to remedy your problems.

For the guys with no low-speed fan this is due to the resistor failing. Again this resistor is not sold separately (to my knowledge) and used to require complete replacement. There has been some collaboration on the NAM website to fix this. A few members have purchased resistors and used them to bypass the faulty original. If you have a late-model car this should be a simple fix to wire up. The early cars will take a little more patience since the relay is on the fan housing. I purchased one of these resistors and will be installing it on my 11/2002 build Mini very soon.

Hope this helps, there's plenty of info on the NAM site on this fix.
Josh
 
#28 ·
Fixed!!

Hey all

Had a similar problem to some others here - the fan quit and the mini overheated. Tracked it down to a fault in the relay, as mentioned on previous posts.

Mini (BMW) don't sell the relay on it's own - just the whole thermo fan unit. I did the following...

Checked the fuse for the Fan - all good. swapped the relay for the identical Battery Fan relay in the fuse box - no change, and switched it back.

Used a motorbike indicator to verify that power was getting as far as the plug connection, on the front left of the car, very near the hood release lever. All good.

This is serious now...

Download the Workshop Manual for the Cooper S - US$16.99 from emanuals, and an awesome product. Endorsed ;-)

Pulled the front bumper off - very easy. 10min?

Manual said to drain the coolant to pull the radiator, but I didn't need to.

Pulled the front aluminium crossbeam off - 5 x 13mm bolts and nuts each side - done.

two 10mm (?) socket bolts released the aircon condensor (the little radiator). Lowered the left corner to the ground gently and tied the left corner loosely so it would not fall over, therein damaging the hoses that it connects too.

Released the two plastic catches that hold the radiator in (noting that if you remove or unclick the air intake scoop from the plastic surround above the radiator, it is MUCH easir to get at the back of the three pronged bayonet on the car's left hand side!

removed the upper radiator hose only, (no coolant was sacrificed in the repair of the vehicle ;-)

Release all of the wiring harness from the previously mentioned plug fitting, all the way through to the thermo fan.

Tip the radiator towards your thigh then reach down and release the plastic hooks down the bottom, and, quite simply, slide the thermo fan out, freeing the electrical harness from fowling as you go (wifey very handy for this task).

Once release I cut the wires from the relay box to the fan motor at a point where I could easily rejoin them later with bullet fittings. Hooked the fan motor up to a battery pack (keep your finger clear!!) All good, works a treat.

two screws released the relay cover. The relay has 40Amp and a diagram on the back to show how the two small wires (the small plug you disconnected earlier) provide power to switch the big wire (big Plug) power supply between hi and low.

Raced down to the auto warehouse (AutoBarn), found a suitable 5Pin, 40Amp that would switch appropriately, (same diagram on the relay - easy), raced back and pushed it into the same relay receiver).

Tested - all good.

everything else was just the reassembly, electrical, heat shrink and zip ties.

Tip, tricky getting the locator spacers (they look like thick, domed washers on a bolt that fits into a hole on the cross member) to fit the cross member on reassembly. They are a loose fit and like to 'hang off the bolt. It will make sense when you see it. Get someone to hold one side on, in the right place (easily done), put the loop of a wire around the domed spacer and hold the two ends of the wire vertically above the cross member as you ease it into position. A vertical jiggle (technical term) of the wire will allow the spacer to find it's mark, the member slides on and you release one end of the wire, pulling free and start securing the bolts again.

$700 job cost $10.99. Parts required, Work Shop Manual, Phillips head screwdriver, socket set with 8mm, 10mm and 13mm sockets, vice grips (for the clip on the upper radiator hose, makes it easy), a bit of wire and a 40Amp , 5Pin Relay based on the one you 'pull'.

Takes about three hours with 4 beers, 2 hours with a coffee instead :biggrin:

Hope it helps. let me know if you have questions.
 
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