2006 Hdi Pug 207 cooling fan

[Geoff Lebowski]

Hi,
I\'m asking on behalf of my neighbour and trying ot help out

Problem is apparently simple: The Radiator fan continues to run after the engine is turned off. Normal behaviour I believe, but normally for a few minutes or so. This one doesn\'t turn off at all and flattened the battery.

She called the AA who diagnosed water in the engine bay fuse box and that it needs to be replaced. However, the fuse box and all the gubbins looks unaffected by water/corrosion of any sort.

My immediate thought was more a faulty coolant temp sensor fault, causing a permanent \'engine too hot reading\'

I\'m used to older cits, where they would use a normally open switch, thus closing when coolant temp is too hot. I understand however that more modern units will use just one sensor but the ECU will control all activity.

Can anyone shed any light on possible causes and simple multimeter tests I could carry out. This suggested fuse box replacement looks an expensive item could be a costly red herring

many thanks

[spider]

I think if the sensor reads faulty it will indicate just "high" all the time which will also cause the stop light to come on which is something that you would notice.

206's (petrol) used to do this sometimes.

You are correct in that its normal for the fan to be permanently supplied although it should stop after a few minutes.

Take a relay / fuse out of the fusebox and examine both the relay and the fuse box contacts. Relays can fill with water (not that common but annoying)

I don't know the 207 as it was not out when I left, but the older models sometimes had the fan relays at the front (usually three relays) these were a bit susceptible to the elements.

[Geoff Lebowski]

Thanks Andy, I think I know the three relays you mean, my Xantia was the same, mounted on the fan housing???? I can\'t see if this is the same without stripping the car down.

I know, typically, there were three sensors, 1 for temp guage, one for switching purposes ( warning lights and fans on) and the other for engine ECU. I had read somewhere that all three had been replaced by one sensor that fed all info to an ECU and then it was the ECU that flashed up the necessary warnings etc.

Anyway, I hadn\'t considered the stop lamp, which infers that no sensor is at fault but that a short to the fan is causing this problem. As you suggest, the relay could be at fault and/or the fuse urred up and shorting.

I also unplugged the feed to the fan itself, which was full of water!!! Reconnecting after letting it dry for a few minutes didn\'t solve the problem.

[spider]

My thoughts are still with the relay or wiring, so we kind of agree.