This is baffling me and I would like some assistance, if possible, please.
My cooling fan won't kick in even if I leave the car running for an hour, the catch is, the engine doesn't show its overheating on the temperature gauge, but surely it should after that amount of time, I know it works because it went all the way up when I lost all the coolant the other day through a faulty after market expansion tank cap. I also know the fan works because when I switch the heater on the fan works. I have changed the engine cooling sensor and both the relays under the bonnet, not to say that they are faulty but I doubt it, as it was like this when I bought the car a few years ago .I have also checked the fuses under the glove box which are all good. The only thing I haven't changed is the thermostat, could that be what's causing this?

Hi Nissaki, I have had this problem up to an hour ago when I was selling my 2006 1.25 Zetec Fiesta to a car garage owner. The fan works fine when power goes directly from battery to it, but would not simply come on even after changing the thermostat, fan sensor, relay. I looked at everything and could not figure it out. I did not get it fixed - but a temporary solution for the fan to come on to get you moving till you have extra time to look at it further - is by removing the electrical cable of the sensor - fan came on straight away. I was dumbfounded when the garage man looked it the car and sorted it out within 3 minutes. I if had known this I would not have been selling the car, but there you go. Try it and let me know if that works as a temporary measure. Good Luck. 

What a brilliant tip, thank you I will give that a go at least that will last until the weather warms up and I can have a really good look at fixing the problem once and for all.