Electric fan problem

Harshan · Post by **Harshan** » Wed May 23, 2007 6:20 am

Hi all,

My D8 has a problem that is when I switch off the ignition, electric fans run for few seconds and then goes off.. even if the temperature is more than 90 degrees. If I switch on the ignition then both the fans comes in the normal speed.. As I know it should run for a while even if the ignition switch is off. And if the heat is more than 100 fans keep running even if I switch off the engine. Is this normal or I'm near by some problem..?? Any help will be really appreciated.

mjb · Post by **mjb** » Wed May 23, 2007 9:27 am

Sounds about right to me.

Harshan · Post by **Harshan** » Wed May 23, 2007 9:54 am

>>Sounds about right to me.

How does yours work.. if u stop the engine sooner the fan engages .. with A/C off ? would that keep running or stop after 2 seconds?

darrenwall · Post by **darrenwall** » Wed May 23, 2007 10:11 am

Harshan wrote:Hi all,

And if the heat is more than 100 fans keep running even if I switch off the engine. Is this normal or I'm near by some problem..?? Any help will be really appreciated.

over 100 seems a bit hot , i thought both fans are supposed to kick in about 95 to cool it down

my old 405 used to run that hot just before the head gasket went

Harshan · Post by **Harshan** » Wed May 23, 2007 10:24 am

thanks darrenwall for the reply.. mine works like this

1 with no A/C (when temp increases to 92) - both fans on in low speed
2 with A/C - both fans on in low speed
3 with A/C (when temp increases 92) - both fans on in high speed

4 When ignition off while fan running (temp over 92) - fans goes off
5 When ignition off while fan running (temp over 100) - fans continue

Number 4. isn't sounds right to me.. according to my friend fans should keep running even if switch off the ignition until temp decrease below 92 .. but that doesn't happen ..

mjb · Post by **mjb** » Wed May 23, 2007 11:15 am

I've never had mine go over 95-96 but everything you've said sounds like the correct operation. 406s only run the fans with the ignition off if the temperature's over 100 purely as a last ditch attempt to cool the engine bay before something dies horribly. This is because the coolant pump is run straight off the engine (as opposed to being electrically driven) so once you kill the ignition, you've lost coolant circulation and turning the fans on would do very little to help - there's no point cooling the coolant in the radiator if you've still got boiling hot stuff in the engine

I'd guess if your car's hitting over 100 you should investigate why as something's going to break as a result sooner rather than later!

Aircon needs airflow to work, which is why the fans operate more aggressively with it switched on.

Post by **Welly** » Wed May 23, 2007 11:31 am

Actually m, if you cool the water in the rad then it will move some water out of the block through conduction circulation. Fluids of different temps will circulate (to an extent) without a pump as long as the thermostat is open.

mjb · Post by **mjb** » Wed May 23, 2007 11:47 am

I did ponder that, but wouldn't the pump being mechanical mean that it's effectively a closed valve when not moving?

Post by **Welly** » Wed May 23, 2007 12:43 pm

Well the pump is only an impellor within a housing, with some tollerance around the blades etc so water can flow through there - albeit restricted.

If water wants to go somewhere then it will do.

406oc.co.uk

Electric fan problem

Electric fan problem

Re: Electric fan problem