Help!!!! Fan switch.

**Nealevo** · Friday 13th September 2013, 18:38

Ok how many fan switches does the 850 T5 engine have? When I was sitting in traffic at TRAX I noticed that my temp gauge when north, and my fan didn't cut in, I have had thermostat replaced with the sensor thingy underneath and I brought a new relay from Volvo today (robbing Barstewards) but the fan is still not cutting in, if you put a direct feed to the fan it works perfectly.... So suggestions before it goes for filming in Thursday!

**graemewelch** · Friday 13th September 2013, 18:48

have you tried the engine temp sensor. sorry not much help. not very clued up on these

**smithy** · Friday 13th September 2013, 18:49

Check to make sure the pipes are hot because if you have done all that then the fan should work .

**hybriduno** · Friday 13th September 2013, 19:01

when I disconnect the sensor on the thermostat my fans kick in. as far as im aware the ecu controls the fans low and high speeds via temp if that helps lol oh,and mine takes about 25-30 mins on tick over before they come in

**stribo** · Friday 13th September 2013, 19:06

Is the fan controlled by the temp sensor, or the ECU? If it's from the sensor then stick 12V on the fan side, to make sure there's no break between the sensor, and fan. If it's controlled by the ECU, then don't do that as the ECU won't like 12V sent straight through it. (A mistake I made on a Mondeo I had)

Edit: Looks like Adam's just answered my question.

**hybriduno** · Friday 13th September 2013, 19:24

Originally Posted by stribo

Is the fan controlled by the temp sensor, or the ECU? If it's from the sensor then stick 12V on the fan side, to make sure there's no break between the sensor, and fan. If it's controlled by the ECU, then don't do that as the ECU won't like 12V sent straight through it. (A mistake I made on a Mondeo I had)

Edit: Looks like Adam's just answered my question.

the fans are controlled via 2 switching earths one for low fan spin and one for high fan spin , I have put switches on the volvaxo to both that earth out

so I can have fast or slow fan speeds

**merc85** · Friday 13th September 2013, 19:25

The fan is powered by the green wire which has a fusable link within the loom. it feeds a constant 12v supply to one side of the relay, when the temp sedor get the signal to the ecu the fan starts. Sounds like you fuseable link is well fused lol.

Run a 12v supply to the relay from the battery mate and it will sort it out. I had exactly this in traffic in london. Hope this helps

**p fandango** · Friday 13th September 2013, 19:31

Originally Posted by hybriduno

the fans are controlled via 2 switching earths one for low fan spin and one for high fan spin , I have put switches on the volvaxo to both that earth out

so I can have fast or slow fan speeds

correct, there are 2 yellow wires (1 with a white stripe) on the fan control relay. Earthing these will bring the fan on, 1 is high speed the other the lower

**craigoodwood** · Friday 13th September 2013, 20:27

when i had a remapped ecu in my last t5, that wouldn't work the fan but when i stuck the standard one back in it worked fine, it turned out to be some of the female prongs not touchin the ecu if that helps too...

**Nealevo** · Saturday 14th September 2013, 11:47

Originally Posted by merc85

The fan is powered by the green wire which has a fusable link within the loom. it feeds a constant 12v supply to one side of the relay, when the temp sedor get the signal to the ecu the fan starts. Sounds like you fuseable link is well fused lol.

Run a 12v supply to the relay from the battery mate and it will sort it out. I had exactly this in traffic in london. Hope this helps

All sorted, thanks Gav xx

**Harvey** · Saturday 14th September 2013, 11:53

Good news there,so it's back to giving it a quick once over then put away till Thursday.
Do they know what your day job is ?,you never know they might have some other toys you could have a play while they use yours.

**V70 Graham** · Saturday 14th September 2013, 12:02

I generally have the opposite happen, the fan will stay on quite a bit.....but then I do drive 'on the edge' most of the time lol

**Harvey** · Saturday 14th September 2013, 12:08

Originally Posted by V70 Graham

I generally have the opposite happen, the fan will stay on quite a bit.....but then I do drive 'on the edge' most of the time lol

Things change at speeds above 39mph ,like the air is pushed through the radiator so it doesn't need to sucked through by fans which take bhp away from the engine.