Hello. Context is key: 2005 1.9 TDI estate (is estate relevant? Hmm...)

Anyway for the last... let's say roughly two years I've noticed the fan is audibly running more than it used to after turning the engine off. Only for 15 seconds or so, so that isn't the issue, but it's only the larger fan.

I never seem to see the smaller one on the left turning. Yesterday I had a long drive and it was about 30 degrees and the large fan ran for about a minute or two after stopping.

So... I am not concerned about the large fan being on, as it operates correctly and does not get stuck on, and the engine does not overheat (never over 90 on the dial) but... should both fans run?

Is the large one having to compensate which is why I've noticed the large one doing more work?

Oh by the way, my wife has offered a diagnosis of "extreme paranoia", or in other words the issue lies between the chair and the steering wheel.

Can you please share the reg plate or VIN with me so that I can look up the relevant schematics and parts info.

I think the two fans should probably operate together, but need to check.

3 minutes ago, Breezy_Pete said:

Can you please share the reg plate or VIN with me so that I can look up the relevant schematics and parts info.

I think the two fans should probably operate together, but need to check.

Sure the VIN is TMBJS21zx52065473.

The fuse is ok and the small fan can be moved by hand freely so if it is meant to be running I guess the fan is just dead.

Looks like the fan control module is integrated into the main fan, with the smaller fan powered from it, so not quite as clear-cut as if I'd found a circuit showing the fans wired directly in parallel, like many of the earlier versions are.

I still think they should probably run together, so maybe try powering the small fan directly with 12V, to see if that makes it run (disconnected from its big brother/sister).

Edited 20 June, 202520 Jun by Breezy_Pete
sp

5 minutes ago, Breezy_Pete said:

Looks like the fan control module is integrated into the main fan, with the smaller fan powered from it, so not quite as clear-cut as if I'd found a circuit showing the fans wired directly in parallel, like many of the earlier versions are.

Is still think they should probably run together, so maybe try powering the small fan directly with 12V, to see if that makes it run (disconnected from its big brother/sister).

Thanks for looking. That's where it slips from "would check myself" to "haven't the time or skills and a mechanic might well laugh at me".

As an alternative, if you have a multimeter, you could measure the volts between pins of the connector that comes out of the big fan towards the little fan, to see if there's 12V there when the big fan is running. Just be careful fingers etc don't get involved with the big fan.

26 minutes ago, Breezy_Pete said:

As an alternative, if you have a multimeter, you could measure the volts between pins of the connector that comes out of the big fan towards the little fan, to see if there's 12V there when the big fan is running. Just be careful fingers etc don't get involved with the big fan.

Cheers, though afraid I've not got one.

5 hours ago, Breezy_Pete said:

Can you please share the reg plate or VIN with me so that I can look up the relevant schematics and parts info.

I think the two fans should probably operate together, but need to check.

You wouldn't at all be able to identify the part number of the smaller fan, would you?

Yep, can look up next time I get up.

28 minutes ago, Breezy_Pete said:

Yep, can look up next time I get up.

Cheers.

It came on again earlier after a short drive to the shop; I managed to get the bonnet open in time to confirm it was only the larger of the two spinning.

Then arriving back at home (again short drive!) it was on for a minute or two after switching the engine off. But it is c. 30 degrees again and low speed, local drives.

Small fan is 1K0959455DG which has been superseded by 1K0 959 455ES, a mere £270 + VAT at Skoda😆

Described in parts list as 290mm, 150W, Siemens.

Edited 20 June, 202520 Jun by Breezy_Pete

6 minutes ago, Breezy_Pete said:

6 minutes ago, Breezy_Pete said:

Small fan is 1K0959455DG which has been superseded by 1K0 959 455ES, a mere £270 + VAT at Skoda😆

Described in parts list as 290mm, 150W, Siemens.

Amazing cheers.

One thought I had, some meat on the context... a few weeks ago I had the water pump replaced and overnight the coolant level dropped as there must have been air in the system. It dropped to juuuuuust above the bottom of the tank... I could see a bit of pink fluid above the pipe out.

The garage said just to top it up with water. I'd say the water content is about 750ml, sufficient to take the level from the bottom of the tank to the minimum line. When cold, the liquid sits on the minimum line.

BUt now I am thinking... a) would the water be preventing adequate engine cooling, as it isn't suited to the job as much as coolant is, and b) would it do to keep the level higher than minimum (halfway say between min and max).

Anyway I wonder if this is a cause for the recent increase in fan activity too so will replace coolant and see how that goes.

2 minutes ago, JamieH86 said:

would the water be preventing adequate engine cooling, as it isn't suited to the job as much as coolant is

Nope. Water is superior in outright heat capacity.

Don't waste your time.

4 minutes ago, Breezy_Pete said:

Nope. Water is superior in outright heat capacity.

Don't waste your time.

Cheers. Well I found a 1K0959455DG on eBay with all the right specs so I can have that in my back pocket if the garage says it needs replacing, or return it if not.

Remind me whereabouts you're based?

19 minutes ago, Breezy_Pete said:

Remind me whereabouts you're based?

Cwmbran, old south Wales.

Not really close enough for in person help. I'm 1:20 away just north of Swindon.

Edited 20 June, 202520 Jun by Breezy_Pete
sp, as usual

20 minutes ago, Breezy_Pete said:

Not really close enough for in person help. I'm 1:20 away just north of Swindon.

True. Mind you we will be in Yate this weekend, but I certainly don't expect you to have to help!

Well for the last few days things have been normal. The temperature has dropped to around 20 which has helped I guess. Fan still on after long drives but stops fairly quickly so all normal.

However today I did notice the temperature needle was around 95/100 degree area (hard to tell as not all numbered) which is unusual.

On the other hand sometimes my dials (fuel, revs and temp) sometimes start at the "wrong" point so they always read too high or low.

I only noticed the temperature literally as I pulled onto the driveway so I turned the engine off, then turned the key one click back on to engage the dials, and the temperature went to and stopped bang on 90. So maybe it had been over-reading before.

Will keep an eye on it, anyway!

Well having got to understand my dial better, the specific reading earlier was 92.

However, on driving to Bristol from South Wales... no issues. Got up to 90 and stayed there.

On the return trip, the same (mostly M4).

But right at the end, to get to our road is a steep hill and a sharp right. At that point, it went to 92, then by the time I was home and level it was 90 again.

So... I can't be arsed to worry about that. The fuel guage does similar of course, going up and down slightly if I am going down or up hill, and maybe for some weird reason this hill and corner does similar for the temperature.

Not that I can think how! A sensor somewhere maybe? I know the engine isn't actually overheated as when you turn it off and on again, immediately it is bang on 90 (and the fan hasn't even stayed on).

Well this went quiet when the weather cooled and I thought I could put it down to that.

However we drove to Poland this weekend and the temperature behaviour got increasingly odd.

Our trip was essentially three drives of five hours apiece (Wales to Harwich, Hook of Holland to Hanover, Hanover to Poland).

DRive 1 - normal. Temp stayed at 90.

Drive 2 - temperature went up on hilly stretches (there was one very big hill at one point, about five miles at 30-40 degree incline), as high as 100, then back down to 90 on flat/downhill.

DRive 3 - stayed at 90 if at 40mph or below but above that seemed to stay over temperature with the speed. Ie. 50 mph, engine at 92°. 60mph, 95°. 70mph, 95-100°.

Sometimes that would go down to 90, sometimes it would stick. Hills not really a factor. Any acceleration (for instance, going from 50mph to 80mph on leaving roadworks) seemed to accompany a rise in temp.

No warning lights and no temps outside the "safe" zone... but this is not usual for this car.

The water pump was replaced a few weeks ago (from the Quinton Hazell kit QBPK6250 Timing Kit & Water Pump).

Coolant seems steady, no gak in the oil.

Sorry no 100% right above... I did have to top off the coolant (it was at the halfway point when hot as opposed to over the max line) and there has been since the new pump was fitted (*POSSIBLE* coincidence alert) a squealing from the front offside of the car, particularly on slowing/moving off.

I Have read this could be the pump belt or pulley?

For those following this, the issue seems to have been an elderly thermostat.

The coolant level (no internal or external leaks) would vary as and when the thermostat stuck closed, and the heater started blowing cold in the cabin.

The coolant was well "burped" and the temperature changes were not consistent with an air lock, but rather improper circulation of coolant at higher speeds.

I guess this could have been going on gradually for a while, hence the much more minor things I initially noticed and mentioned here.

New thermostat going in today!

One new thermostat and 800 miles later and all is well. Very much improved performance and even after a long and heavy drive (some big hills, five people in the car, full boot etc) no change from 90° on the dial and in fact so well managed now, the fan didn't even need to run after turning off the engine.

It would have been a cheap and easy month had I not also broken a shock absorber on a particularly "cheeky" bit of Polish road...