Ford Fiesta - Radiator fan not working

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Wed 10 Jul 2019 14:58
Ford Fiesta - Radiator fan not working - Chris M

Possibly one for elekie.

The fan isn't coming on on my son's 2009 Fiesta with climate. It's not running either with the climate on or when the engine gets hot. I've only checked the fuse is ok and the fan is free to turn.

It's been suggested that the first check should be the temperature sensor. My only thought is that when the engine gets very hot, the temp warning light comes on (no temp gauge). If the sensor was faulty, would the light work? Or is there more than one temp. sensor? I couldn't see one on the radiator, but I was wearing decent clothes so my inspection was limited.

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Wed 10 Jul 2019 16:18
Ford Fiesta - Radiator fan not working - elekie&a/c doctor
There is no dedicated temp switch for the fan , it is controlled by the engine temp switch and engine control unit. It may be that the fan motor is in trouble , but the circuit to it needs testing. There is a relay and fuse by the battery. In the fuse box if it is the later model.
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Wed 10 Jul 2019 18:07
Ford Fiesta - Radiator fan not working - skidpan

As far as I am aware in these newer Fords there is one sensor that as elekie says is connected to the ECU and sends signals to the fan, temp gauge idiot light etc. If the temp gauge is working the sensor is obviously OK and the problem is elsewhere.

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Wed 10 Jul 2019 20:59
Ford Fiesta - Radiator fan not working - Chris M

Thanks elekie.

Well, disconnected the plug to the fan and checked for current. All ok so thought it must be the fan. Removed it (remarkably easy!), Connected 12v and it works! The plug connector is clean with no corrosion, so I don't know what's going on. Wiggled the wiring about in case there's a break. Still works. A bit stumped as to what the problem was, or maybe still is. Will have to keep an eye on it.

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Wed 10 Jul 2019 21:38
Ford Fiesta - Radiator fan not working - elekie&a/c doctor
You have confirmed there is power to the fan motor, but what about the earth to the motor .? This part of the circuit is often overlooked.
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Wed 10 Jul 2019 23:43
Ford Fiesta - Radiator fan not working - Chris M

I used a meter across the two contacts having first checked that there was earth continuity.

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Thu 11 Jul 2019 00:28
Ford Fiesta - Radiator fan not working - elekie&a/c doctor

I would load test the earth circuit using a headlight bulb. Using a meter might show earth continuity ,but not adequate to pass the high current of the fan motor. If the a/con is working, the fan should cut in after approx. 30 seconds of operation.

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Thu 11 Jul 2019 16:02
Ford Fiesta - Radiator fan not working - Chris M

The fan is working as it should at present so I don't think it's a bad earth, but nevertheless worth checking where it's grounded to the body shell. Any idea where that may be (green/black wire)?

Do you think there could be a fault/loose connection within the motor itself. Seems strange that it works following removal and refitting.

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Thu 11 Jul 2019 17:12
Ford Fiesta - Radiator fan not working - elekie&a/c doctor
Possibly resurrected a poor connection. Earth point is possibly on the chassis, below battery or headlight. Just monitor the situation.
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Thu 11 Jul 2019 20:46
Ford Fiesta - Radiator fan not working - Chris M

Thanks for your help elekie. Appreciated.

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Sat 20 Jul 2019 12:54
Ford Fiesta - Radiator fan not working - Chris M

Update in case it helps anyone in the future.

Fan stopped working again this week. A sharp tap with a piece of wood got it going so thought time to find another one. A genuine Valeo one is £80+ online so I thought I'd try the scrapyard first. They had 6 Fiestas, but only one still had the fan so maybe it's a common failure. £20 later and we have a working fan.

Being inquisitive I took the old one apart to see what was wrong. Two out of four of the brushes are virtually non existent. The second hand one may be almost as worn, but we'll have to wait and see.

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