Engine fan doesn't turn off.

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Ah2
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Drives: Polo r6
Location: London

Engine fan doesn't turn off.

Post by Ah2 »

Hi guys,
I have polo 6r and yesterday I realised my fan is staying on and running down my battery. Any advice on what could be the cause of this?? Im Completely lost!
RUM4MO
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Drives: B8 S4 & 6R/6C1 1.2TSI 110
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Re: Engine fan doesn't turn off.

Post by RUM4MO »

I'd think that it is one of three things:- fan control module faulty, ie stuck/welded contact(s), temperature switch that controls the fan(s) faulty, a wiring problem in between the two.

Edit:- to prove that it is not the temperature switch's fault, unplug the connector mounted on it. To check that it is not the wiring to the fan control module, unplug its control plug, ie the small one.
Ah2
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Re: Engine fan doesn't turn off.

Post by Ah2 »

Thanks buddy... Where is the temperature switch located if you don't mind me asking?
RUM4MO
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Joined: Sat Dec 30, 2006 9:12 pm
Drives: B8 S4 & 6R/6C1 1.2TSI 110
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Re: Engine fan doesn't turn off.

Post by RUM4MO »

I've not looked for that on this mk of Polo, but typically it is on the radiator or a pipe close to the radiator.

Edit:- maybe tell us the engine and trans fitted to your car as I have a Haynes Polo 6R repair manual.
RUM4MO
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Joined: Sat Dec 30, 2006 9:12 pm
Drives: B8 S4 & 6R/6C1 1.2TSI 110
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Re: Engine fan doesn't turn off.

Post by RUM4MO »

Haynes says "left hand side of radiator" - which means passenger side for RHD cars, for the location of the thermostatic fan switch - remember in some cars this switch will have 2 settings, obviously OFF when coolant is cold enough, ON-1 when coolant is over 90C and ON-2 when coolant is over 110C.
These are rough temperature figures, but on some Polos the fan will be 2 speed, so the slow speed gets switched on first to control/reduce the coolant temperature, if that is not enough fan cooling the temperature rises and the second switch position changes the fan speed to fast speed.
What can also happen is, the series dropper resistor burns out and so goes open circuit, so you end up with no slow speed only slight over heating then fast speed running of the fan.
You can tell if the fan is 2 speed by the number of wires going to the motor assembly, originally in most VW Group cars there were 2 cooling fans, both only ran at fast speed, but someone seemed to have a cunning plan to save a bit of cash and drop this down to 1 fan with 2 speeds.
Ah2
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Drives: Polo r6
Location: London

Re: Engine fan doesn't turn off.

Post by Ah2 »

Hey guys, thanks so much for the advice. It's a polo MK5 engine size 1.2 manual.
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