Radiator fan operation and ignition state.

[aclwalker 3]

Last night when I turned off the engine I noticed (as often happens) that the fans turned on, drawing air through the radiator. This normally goes off itself after a minute or two, as, I believe, is normal.

 

However, I quickly turned the electrics back on this time because I wanted to see what time it was and noticed that the fan immediately switched off again. So I put the ignition off and on a few times to see and the fan went on and off with the ignition: fan off when the ignition was on, and fan on when the ignition was off.

 

Is this normal? I would have thought that once the fan came on, it would have stayed on, regardless of ignition state, until the temperature had fallen to the appropriate level.

 

Does this point to a faulty temp sensor or am I worrying about nothing?

 

Thanks.

[bix 0]

Mine does that too, and also when you leave the car and the fan runs, it seems to stop and then run again, and stop, then run again for ages :? no idea why but I'm sure it shouldnt do!

[aposegil 0]

in our cars with have a fan over run switch (normal brown round sensor that sits at the back of the engine over having the cam cover or in G60 engines above the injectors not sure the vr's) which detects the temp of the engine bay after uve turned the car off

 

if they are to high they wil turn on by themselves and off once it lowers down (bit like the fan switch in ur rad)

 

the reason they turn off when u put the key back in the ignition is that one it stops the fans so you have full power to start the car and two it assumes ur going to start it which normal fan operation should take over so no need for it as ull also have the water pump puming the water round the engine bay.

[aclwalker 3]

Thanks.

[DelMonty 0]

Mine does that too, and also when you leave the car and the fan runs, it seems to stop and then run again, and stop, then run again for ages no idea why but I'm sure it shouldnt do!

 

Sounds like your auxillary water pump has given up. I know this as mine recently gave up, and now instead of the fans running after the igintion is switched off for a set time, it turns on, off, on off, as the area where the thermostat is located is only being temporarily cooled by the air, the actual water is no longer being pumped round the system by the aux pump, which is also meant to run when the ignition is off and the engine is hot enough for the fans to cut in.