Radiator fan at 4.00AM???

[stephencoley]

This is a slightly bizarre one that I'm hoping somebody else has encountered...

Last weekend we took Clara, as our lovely van is called, for a little trip out to Staffordshire. We pitched up on the Friday night and never drove the van again until we left on the Sunday morning... Well, after going to bed on Saturday night, amid the monsoon weather, we were woken at about 4.30AM by the radiator fan noisily whirring round Engine was obviously off, keys weren't even in the ignition. More than a little confused (I generally am at 4.30 in the morning!!!)I began to check switches. Eventually I unplugged our mobile-phones which we'd left on charge and the fan stopped. About an hour later the fan sprang into life once more, and this time the only way to stop the thing was by actually starting the engine. As soon as the engine started the fan stopped... So there you have it.

What could possibly cause the radiator fan to start up in the middle of the night??? And just to point out, our fan has been working perfectly before and after the incident last weekend. I don't know if the extreme weather could have affected anything???

These campervans are fun aren't they

[ghost123uk]

The fans temperature sender closes a relay to power up the fan, I am pretty sure it does so by "earthing" the relay's coil output, so the only possible cause I can think of is the wire between the sender and relay is chaffing on some bodywork and "earthing out" = some movement in the van, like you moving around or firing up the engine could make that wire move, making / breaking it's faulty connection with "earth".

Eventually I unplugged our mobile-phones which we'd left on charge and the fan stopped.

There can be no connection here (except for the above mentioned moving about)

These campervans are fun aren't they

[AdrianC]

I've had a fan temp sensor fail "closed", randomly, before. I happened to walk past the car one snowy afternoon, not even having started it for a day or two, and the fan was on.

Just disconnect the plug from the sender, and it should stop. It's behind the LH end of the lower grille - you might not even need to remove the grille, but it does make it easier. New sender, and it'll be fine.

[stephencoley]

Thanks people... I'll investigate further.

Being woken at 4.30AM is a fairly major issue in my book

[pirate-pete]

I too think duff temp sensor in the radiator as mine also came on full speed by itself at while parked but luckily neighbour heard it and thought I'd left engine on. Until I got round to replacing it I stopped it by removing the fuse which I'm pretty sure on my early style fusebox powered nothing else.