can anyone help the radiator fans are not cutting in?

 

Would a knackered coolant temp sensor cause this? i.e. perhaps it doesn't put out a voltage that represents the 91deg C when they come on?

Do you have access to a decent digital water temp gauge e.g. on a PFC Commander maybe? That way you could go hooning and then deliberately "get stuck" in slow traffic, or park up, and see what's happening...?

 

Or maybe the thermostat is stuck open? I think, however, that the OEM one, when it fails, actually fails in the shut position. So temps would actually rise (rapidly).

 

where is the coolant temperature?

 

Across the top rear of the block is a large ally "coolant crossover" pipe. There are 2 brown sensors next to each other at the rear of this pipe (bulkhead, driver side). The CTS is the larger of the two (the small one is the temp gauge sender).

 

That image is unfortunately rotated -90deg lol.

The 'top' is facing left.

The CTS is the big terracotta/brass coloured thing.

 

i always thought that when the sensor broke the fans came on from cold

 

I've heard that too. But whether that scenario happens ALL the time, don't know(?)

 

see if you can get some fans cheap there easy to change, change your coolant with fresh anti freeze too it the sensor might be furred up inside as there not the easiest things to change, lots of bits n bobs in the way

 

you say the fans dont come on, do they need to ? i mean,is the temp gauge past halway,3/4 way/you have an overheating car ??

 

well my last engine i cooked the head gasket it sed the car was coool on the temperature gauge but i never heard the fans running ive just done a engine change and still no fans *** on?

 

The ECU is programmed to activate the fans only if the coolant temperature exceeds 96 degrees celsius (and switches them off again at 92, if I remember right).

As such it's possible that your engine and sensors are all functioning properly but you haven't yet got the coolant hot enough to cause the fans to kick in.

It's also possible that you have damaged fans, damaged fan relays, or, as has been said above, a defective engine coolant temperature sensor.

The one thing you could try is connecting the green plugs under the dash to put the ECU into test mode, and then turn on the ignition. You should see the fans sequentially switching from off to low, then to high, and off again constantly. If you don't see them doing that you should be looking at the control relays, wiring, the fan motors or possibly a fuse.

If you do see them coming on in test mode, then there are pretty much just two explanations left for you not seeing them on when driving normally. Either the engine coolant temperature sensor is defective, or, as above, everything's fine and you haven't yet got the car hot enough to trigger them.

 

both fans do turn on when in test mode