26 replies to this topic

[Dog.]

Hi all,

Trying to diagnose why my fan isn't turning on properly, and I was wondering;

Is the Water Temp Switch that's in the Thermostat Housing, which turns the fan on at a certain temperature, also the sensor for the Temp. Gauge in the cabin?

Because my temp. gauge is working correctly, so if they are both the same thing, then I know I can rule that out :)

Thanks,

Simon.

[Dog.]

Anyone?

[Dylan8660]

If irc its the ecu that controls the fan and that would get the information from the temp sensor. but the mpi runs hotter than other minis, are you sure its not the recent cold spell rather than a fault.

[Dog.]

Well,

I came off the motorway after about 15 minutes of driving at 70, and then had to sit in traffic for another 15 minutes never getting faster than 2nd gear.

I do that everyday, and up until recently, the fan has had to come on every time.

This time though, the temperature went right up, and the coolant fluid start boiling. But the fan didn't turn on at all.

Now, every time I make the journey, I'm properly careful about revs as to keep the temperature down, but it still goes above halfway on the temperature gauge, to the point where usually the fan would have turned on. But it doesn't turn on.

So not sure.

Simon.

[bcjames]

If you want to test the fan actually works, unplug the sender. It should default to 'on' with the engine running. Mine liked doing that

I'd check the mechanicals of the cooling system before the sensors. I had all sorts of problems that I attributed to the temp sender, but a good service of the cooling system sorted my hot running issues.

Edited by bcjames, 06 February 2012 - 09:27 PM.

[Dog.]

Cheers James, I think that's what definately needs doing :)

[charie t]

The ecu sends an earth signal to the fan relay, next to the wiper motor. I can't remember the colour wire off top of my head.

[Dylan8660]

It could also be a thermostat problem.

[Dog.]

Yup, I've worked out the numerous different things it could be:

1. Thermostat
2. Thermoswitch
3. Mechanical Failure
4. Split/Leaking Expansion Tank
5. Fan Failure
6. ECU Code Reading Error

It's just a case of finding out what it is!

[Sprocket]

The fan itself may have packed in, since it is an electrical item, that has a limited life, after at least 11 years, its probiblyt at the end of its life. Not un heard of. The relay is also subject to the same life span. I'd start there and replace the relay frist and also check the fuse for the fan. These are two easy and quick things that can be own without much trouble. If it still doesnt work, you then have to try and test the fan itself, and if that doesn't work, well there is your problem

[Dog.]

Cheers; I've checked fuse B9 in the actual cabin fuse box and that's fine.

The fuse FR1 which also does the headlights etc has not been checked, but I presume it to be fine since everything else on that fuse works fine.

Thanks for the advice.

[Dog.]

Okay, new question; What way can I test whether the actual fan works? Can't think of any way :L

[bcjames]

Unplugging the temp sender should make the fan run continuously. Or put 12v across the fan some other way to make it spin.

[Dog.]

Which plug is the temp sender?

The one plugged into the thermostat housing, or not? :)

[bcjames]

Yes, brown one on the 'stat housing