Radiator Fan won't Switch off!!!!!!!

[locin78]

Hi , i replaced my fan and the temp switch but my fan wont switch off any ideas what it may be? sometimes it does but most of the time it wont i have to unplug it.

Nic

[harlemex]

mine often runs on quite abit after ignition is turned off. Whats the longest amount of time you have let the fan run after the ignition has been switched off?

[ianw3321]

If you have a multimeter and when engine is cold and fan is going disconnect temp switch turn your mm to ohms and put the two leads across the two terminals on the switch, if the meter reads 0 ohms the switch is faulty and get another one. I would bet money it will be the switch, Get a new one.

[locin78]

i let it run for about 25 mins the other day till i turned it of , it is a new switch as the other one did the same or just did not turn on so i replaced it.

Nic

[harlemex]

damn, thats a long time. I dont reckon it is the switch. I assume coolant level is ok? And the oil and coolant temp? Im thinking air lock.

[locin78]

coolent level as been good since i change the rad, i have a new thermostat ,and i think they call  it temp sender it's like a little scerw  they are the only things i have not changed.

[DrewGTI]

wouldn't of thought an air lock would cause your fan to stay on.



my fan on my old mk3 did the same, tried loads of things til i got it to my mates garage and it was the fan control unit (little black box under coolant tank) changed over, sorted! 

[harlemex]

^^ that sounds like your answer. Good advice mate, didnt know about this control box.

[DrewGTI]

yeah, loads on ebay around £10 - £15 


could still be something else but its what mine needed. 

[rubjonny]

disconnect the temp sensor on rad, if it stays on its not that. it could be the fan after-run sensor wire has snapped off and is shorting to the engine block. its a single pin sensor screwed to inlet somewhere, with a single black wire.