Cooling fan doesn't kick in!

[Nissaki]

This is baffling me and I would like some assistance, if possible, please.
I have a 2002 Mk5 ford fiesta 1.4 petrol.
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?

 

[scotman]

You should confirm that the cooling fan is capable of running. Aka jumper wire it to a power supply to confirm that the fan motor functions. You should also confirm that the ground connection is intact.

 

[Nissaki]

The cooling fan works when I turn the heater on in the cabin

 

[Nissaki]

Update from my last comment:- The cooling fan works when I turn the A/C on in the cabin, not the heater!

 

[Handy Andy]

The Cooling Fan relay needs to be checked - and or replaced - best way to try this is just swap the AC relay for the cooling fan one and try the AC and or the warm up - if the fan works in the warm up - but not AC - the one currently in the AC Relay socket needs to be replaced.

 

[Nissaki]

Thanks Andy, I will give that a go