Fan on all the time

[acme]

Afternoon all,

I'm hoping you guys can help, you were all very helpful when I had the previous light sensor issue

For a while I've noticed the fan comes on on my MK5 an awful lot, seemingly even when it's not that hot/the cars not been on a long run. I happened across a similar topic on PH and it seems that the smaller of the two fans by the rad, the one on the drivers side is prone to failing. However doing some searching seems to imply that when they fail they seize, however mine spins freely.

When I turn on the climate the large fan seems to come on, when I turn the climate off the fan stops - as far as I can tell the small fan doesn't operate. I understand due to the heat the AC unit emits the smaller of the two fans should run all the time - is this correct? If the smaller fan does spin freely does this mean it actually isn't broken, and perhaps the ballast resistor (or equivalent of) has burnt out or corroded (2005 MK5)? Does the Golf have a seperate AC condensor, as that fan seems to be by the main rad, I'd assume there's a seperate one as per a car I worked on over the winter?

And the obvious question, does it really matter if the small fan doesn't work, I guess it's just noisier/the bigger fan's getting more of a workout?

Cheers for any help, appreciated.

[doylebros]

http://www.mk5golfgti.co.uk/forum/index.php/topic,120.0.html

Check to see if anyone local to you has a VCDS  allowing a vehicle scan - then they can do a diagnostic test which will test both fans!

[acme]

Many thanks for the reply, much appreciated

Any ideas on the costs of these cables etc?

Cheers

[brady88]

Many thanks for the reply, much appreciated

Any ideas on the costs of these cables etc?

Cheers

The diagnostics cables?...£180 for a Micro-can from Ross Tech...you just download the VCDS software off their website for free.

That one will be enough to diagnose you cooling system components...I'm going through the same problem right now on my mates car ;)

[acme]

Many thanks for the reply, much appreciated

Any ideas on the costs of these cables etc?

Cheers

The diagnostics cables?...£180 for a Micro-can from Ross Tech...you just download the VCDS software off their website for free.

That one will be enough to diagnose you cooling system components...I'm going through the same problem right now on my mates car ;)

Ouch, I won't be able to do that then!

Any thoughts on the fan issues? As posted the big fan comes on & off with the climate control, I think the small one should run when the engines cool, thing is, is it the whole fan unit which needs replacing or a ballast resistor (or VW equivalent of)?

[brady88]

Without running diagnostics I would suggest replacing the small fan, especially if it isn't running at all... this should reduce the workload of the larger fan and stop it coming on all the time.
From what I've picked up over the past few days ;)

[acme]

I'm assuming no actual damage is being done? Just that the big fan is being used more than it should.

I wonder if the resistor/temp sensor is seperate to the fan, seems a bigger job than it should be to replace the whole unit.

Like you I've been researching it over the past couple of days and there seem to be a few conflicting views, though I think sometimes there's confusion between the fan set up on MK4's & 5's, which I understand are different.

[brady88]

There's no harm in trying a new temp sensor first of all.... around £5 for the part and really easy to just plug in a new one.

Failing that its a new fan... or you could leave it the way it is for now. The only think it can really be harming is the fan (possibly your mpg running colder engine temps). It may shorten the life expectancy of the larger fan as its running all the time... but gives you longer to save for a full new unit ;)

[acme]

Temp sensors are easy to fit? Any ideas where/how? As I say given that mine spins and most of the posts I've found imply theirs don't I'm wondering if it's something else.

As you say though could leave as is until I've got the money together or just leave, but obviously being a petrolhead I like my cars to work as intended!

[lee_plum]

The fans have their own control unit and are a common problem for running all the time!

[acme]

The fans have their own control unit and are a common problem for running all the time!

When you say their own control unit do you mean individually?

I'm assuming this is the same as a ballast resistor I changed on another car recently, it corroded due to age/position in the car where it's prone to water ingress etc.

PITA this & does seem to be a well know fault as you say!

Cheers