Hi All,

So my son has a 2006 fiesta zetec s, 

The engine cooling fan isn't cutting in but if I unplug the coolent temp sensor it fires into life

Has anybody else had this issue and managed to fix it.

Thanks

I have a 2007 Zetec S petrol, and fan only seems to run when A/C is on.

It is controlled by two different relays, one switched by A/C and one using the CTS.  Both relays are controlled via the engine management.

What does the temperature gauge indicate that makes you think the fan should be running ? 

If sitting for a period of time it bubbles out of the cap. Which would indicate to Me it needs cooling,

I haven't got the aircon sensor plugged in at the moment on the front drivers side near the radiator as he had an accident and it snapped off, would this cause the fan not to work even with aircon turned off.

18 minutes ago, kharvey1987 said:

If sitting for a period of time it bubbles out of the cap.

Maybe the Cap need replaced.

Already replaced the cap 

The impedance of the sensor should be between 1-6kohm, depending on temperature of coolant.  I suggest that if you can meausure with an ohmmeter, you might get an idea if the sensor is the problem, but what is the gauge saying....?

1 hour ago, kharvey1987 said:

I haven't got the aircon sensor plugged in at the moment on the front drivers side near the radiator as he had an accident and it snapped off, would this cause the fan not to work even with aircon turned off.

Don't know.  

Temperature gauge goes up to the middle and stays there never says its over heating or anything, just got the coolant bubbling like a kettle and then coming out of the cap, replaced the cap and still does it 

There is a chance that the head gasket has failed. This will be causing exhaust gases to escape in to the cooling system and over pressurise it.

Use a Hydro Carbon test kit to check for exhaust gas in the coolant. Kits available from about £18 on the likes of Amazon or eBay.

That is my next Move to rule that out hopefully, the gauge doesn't read overheating or anything

22 hours ago, unofix said:

There is a chance that the head gasket has failed. This will be causing exhaust gases to escape in to the cooling system and over pressurise it.

Use a Hydro Carbon test kit to check for exhaust gas in the coolant. Kits available from about £18 on the likes of Amazon or eBay.

So this morning I don't the test in the expansion tank and the fluid stayed blue and never changed I'm guessing this is a good sign