Mk4 Polo - Cooling fan not working

DavidA

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Jul 18, 2008, 10:23:51 PM7/18/08

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Hi

My Mk4 Polo overheated today because the cooling fan is not working.
I
have checked the fuses. The Haynes manual suggests disconnecting the
cooling fan thermostatic switch and bridging the relevant contacts in
the wiring plug. Trouble is I can't find the switch. Haynes says it
is
mounted on the left-hand inner wing. Not sure which is left side in
their convention. Is this on the coolant reservoir side? Any tips on
how to locate the switch would be appreciated.

Is it easy to replace the cooling fan motor? (It looks quite cramped
in there). If so, is EuroParts the best bet for a competitively
priced
unit?

Best regards

David

Mrcheerful

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Jul 19, 2008, 3:48:47 AM7/19/08

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the fan switch is either in the edge of the radiator somewhere (reasonably
certain that on yours is at the bottom of the rad), or on one of the hoses
/housings at the engine. it will not be on the inner wing, the control
module is on the inner wing (if you have one ). Some vehicles switch the
fan by the ECU, but I don't think yours does.

DavidA

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Jul 19, 2008, 6:34:45 AM7/19/08

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> the fan switch is either in the edge of the radiator somewhere (reasonably
> certain that on yours is at the bottom of the rad), or on one of the hoses
> /housings at the engine. it will not be on the inner wing, the control
> module is on the inner wing (if you have one ). Some vehicles switch the

> fan by the ECU, but I don't think yours does.- Hide quoted text -

Thanks for your reply. Yes, I found the fan switch on the radiator. I
pulled off the plug and linked the 12V pin to each of the other two in
turn. One connection drew ~6A but the fan did not turn, the other drew
0A. So I guess the motor is faulty. I hoped to be able to replace it
myself, but its so cramped around the fan mounting bracket bolts that
I think its beyond my capabilities. Any further advice welcomed.

David

Mrcheerful

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Jul 19, 2008, 6:55:08 AM7/19/08

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while powering the fan have you given it a spin? sometimes if you coax it
into life it will keep going, it may have got stiff to turn over the cooler
months when it will rarely come on, if at all depending on your driving
patterns. can't help with thinner arms and hands.

Duncan Wood

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Jul 19, 2008, 10:11:54 AM7/19/08

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Take the whole fan & radiator cowl assembly out as one & then you can swap
the motor out easily, doing it in situ will be a bugger.

DavidA

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Jul 19, 2008, 3:48:43 PM7/19/08

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Thanks for your replies. I'm mystified on two counts:

Firstly, my comment about testing the motor above was wrong - I was
using my multimeter incorrectly. I now find that linking the 12V pin
on the fan switch connector to one of the other pins does indeed cause
the motor to spin. However, connecting 12V to the other pin causes no
spinning. Assuming this really is a two speed fan (which Haynes
suggests it is) that can only mean a wire in the harness is broken or
the resistor in the motor has blown. However, when I reconnect the
plug and run the engine until the temperature is 90C, the fan does not
come on at all (which is why I find it overheats on a run). So this
implies that the fan switch is faulty. But surely the switch and the
motor resistor are unlikely to both be faulty? It seems to me that the
motor is really only single speed and the fan switch is faulty. Any
thoughts please?

Secondly, I think I would need minute hands to get the motor fan
cowling off. Is it possible that I should remove the battery and
battery shelf to do this?

Advice appreciated! Trying to avoid a high dealer bill.

David

Chris Bartram

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Jul 19, 2008, 4:06:38 PM7/19/08

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Golf IV fan resistors are famed for blowing so that speed 1 fails.

This page:
http://www.nime.co.uk/mk4fans.html

suggests the resistor is in the motor, and lists a module that will do
the same job.

2 speed fans are usually only fitted with aircon IIRC. Does your Polo
have it?

DavidA

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Jul 19, 2008, 5:30:08 PM7/19/08

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> 2 speed fans are usually only fitted with aircon IIRC. Does your Polo
> have it?

No, my Polo doesn't have aircon. I guess that explains that then.

So I suspect the thermo switch is the problem. Any tips on replacing
it?

Thanks.

David

Duncan Wood

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Jul 20, 2008, 7:15:42 AM7/20/08

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On Sat, 19 Jul 2008 20:48:43 +0100, DavidA <dand...@talktalk.net> wrote:

> Thanks for your replies. I'm mystified on two counts:
>
> Firstly, my comment about testing the motor above was wrong - I was
> using my multimeter incorrectly. I now find that linking the 12V pin
> on the fan switch connector to one of the other pins does indeed cause
> the motor to spin. However, connecting 12V to the other pin causes no
> spinning. Assuming this really is a two speed fan (which Haynes
> suggests it is) that can only mean a wire in the harness is broken or
> the resistor in the motor has blown. However, when I reconnect the
> plug and run the engine until the temperature is 90C, the fan does not
> come on at all (which is why I find it overheats on a run). So this
> implies that the fan switch is faulty. But surely the switch and the
> motor resistor are unlikely to both be faulty? It seems to me that the
> motor is really only single speed and the fan switch is faulty. Any
> thoughts please?
>

If the switch has been faulty for a bit then the resistor tends to die.
Polos have had two speed motors since the 70's, change the switch & see if
it's happy.

> Secondly, I think I would need minute hands to get the motor fan
> cowling off. Is it possible that I should remove the battery and
> battery shelf to do this?
>

My memory could be vague here, but you unbolt the front valance,
disconnect the hoses & lift the radiator, cowl & fan out as one.