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Hi, been a long time since i've been on here!

Car was off road for a while so I gave it a jump start and left it running to charge the battery up.

I came back out to find what looked like the car on fire. It was steam from overheating. Coolant all over the floor - thankfully it looked like it came out of the expansion tank top up cap rather than anything blown.

I noticed that the fan was not plugged in - not done by myself.

I plugged the fan in and even with the car off and cooled down, the fan continued at full chat. I assumed there was an issue with the fan relay on the shroud so I bought another fan (second hand) which I have installed. This fan never kicks in even when the car gets hot.

Any ideas? Is there another relay somewhere to control the fan??
 

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Just finished fixing the same issue with my fan. :-D The fan actually has no relay, its connected directly to the battery and it has a little control unit which is connected to the ECU. Inside this control unit there are 3 transistors which are activated by a chip in the control unit. The more transistors that are activated the faster the fan spins. I think it has 2 or 3 speeds. Over time the transiators burn out and your fan just stays on until it drains the battery and you can't start. The control unit is not sold seperately and a new fan costs 200 bucks which is why they unplugged it.

Why they came up with something as complex as this when a simple relay could have done the job is beyond me. But hey, thats what Germans do.
Interesringly the Rover 75 uses the same fans as BMW but instead of the control unit they have a relay...

My fan also never comes on, the only time I ever heard it come on was when it broke so I'm also looking forward to see what others have to say about this.
 
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