Engine Fans Running Constantly when Engine Running

[Fred Duck]

57 Plate 2 litre TDI Laurin & Klement. These last couple of days, the engine fans have started running within 20 seconds or so of starting the car and continue to run, flat out it seems, until the engine is turned off. This happens when starting from both cold and hot. I've looked through previous threads about similar problems but these tend to relate to fans that come on randomly whether the engine is running or not. So far, once the engine is turned off, the fans stop and don't start up. The dashboard temperature gauge shows the same reading it's always done, there are no warning lights lit, the external temperature read out seems accurate, the air con appears to be working normally, the car is loosing no coolant and there are no signs at all of any overheating. In days gone by I'd have changed the fan  thermo switch with this sort of issue but the car doesn't have one having, instead, a 'Fan Control Unit' built into the fan housing. I've pulled the connections to this and they're clean and the under bonnet fuse box is dry and shows no signs of corrosion. I can only assume that it is the 'Fan Control Unit' that is faulty but would be grateful for any other advice others might have before I look at changing it and the fans. 

 

FD

[KenONeill]

Do you have the Climatronic set in "auto" mode? If so, then it's normal function.

[Fred Duck]

No. Same happens when Climatronic is in auto or manual mode or even when it's turned off. This has only started to happen this last two/three days. Had the car two years and during that time, the fans have only come on now and then as you would expect them to. 

 

FD

Edited 17 May, 2017 by Fred Duck

[KenONeill]

In that case I think you're on the right lines; VCDS may be able to confirm or deny the diagnosis.

[Fred Duck]

Regretfully, I don't have any access to VCDS nor do I know anyone who has. 

 

FD

[TheClient]

If the fans come on immediately upon starting, even a cold engine, with Aircon off, there has to be a fault?  Probably the fans or fan controller.  I am not sure if the controller is integral to or separate from the fans.  Not sure VCDS would necessarily record that fault, there is a location of VCDS owners in the VCDS forum threads. You maybe able to PM someone near you, and for some offer of compensation, could read codes.

 

As I say, not totally confident you will get codes for this though.

[Fred Duck]

Many thanks. As far as I can see, the fan controller is integral with the fan being mounted within the fan housing. You can see it in the photo of the reverse side in this Euro Car Parts listing on Ebay - I think, might just be the motor itself.

 

http://www.ebay.co.uk/itm/Autogamma-GA200497-Car-Engine-Radiator-Cooling-Fan-Electric-Replacement-Spare-/332068744506?hash=item4d50d6ed3a:g:fD8AAOSwaEhZEdtz

 

FD

Edited 17 May, 2017 by Fred Duck

[TheClient]

Yes, quite pricey for replacement. I am assuming skoda genuine parts do not offer the controller separately either- you could phone and check though?

 

Other than that - could try wreckers / recyclers as well as used listings in ebay. Of course, with a used part there is no guarantee it was fully functional or how long you will get from it. 

 

Edit: thinking a bit further, is there a  temp sensor switch in circuit related to fan operation at all or are the fans only operated in relation to AC usage?  If there is a sensor it would be a place to start to test that or change it out first.

Edited 17 May, 2017 by TheClient

[Mikek3111]

Did you get to the bottom of this? I've had this issue for ages. Replaced all temp sensors including ambient sensor, second hand fuse box and second hand fan set and still have the problem.

[TK699]

I believe the high pressure switch / sensor on the air con system has something to do with the fans.

 

Could be a knackered switch/sensor.

[meaty101]

4 hours ago, TK699 said:

I believe the high pressure switch / sensor on the air con system has something to do with the fans.

 

Could be a knackered switch/sensor.

 

That part is a common for failing. And would also show up on a scan. I'm just wondering if unplugging it would turn the fans off. It might confirm the diagnosis? 

Edited 28 May, 2017 by meaty101

[TK699]

30 minutes ago, meaty101 said:

 

That part is a common for failing. And would also show up on a scan. I'm just wondering if unplugging it would turn the fans off. It might confirm the diagnosis? 

 

No harm in trying. Logic would say it would go off.

[meaty101]

I'm not too sure but the only problem with disconnecting the sensor is it would flag up a fault which will confuse the issue even further if you had a scan carried out. 

[Fred Duck]

On 27/05/2017 at 12:34, Mikek3111 said:

Did you get to the bottom of this? I've had this issue for ages. Replaced all temp sensors including ambient sensor, second hand fuse box and second hand fan set and still have the problem.

Yes, but only in the last few days. The problem was with the air con pressure valve that was leaking gas. When this happens, the fans go into safety mode and run all the time. Replace valve, re-gas and all back to normal. 

 

FD

[logiclee]

On 5/29/2017 at 12:53, Fred Duck said:

Yes, but only in the last few days. The problem was with the air con pressure valve that was leaking gas. When this happens, the fans go into safety mode and run all the time. Replace valve, re-gas and all back to normal. 

 

FD

 

 

Interesting.

 

My Aircon was working fine, but stupidly I called in at Halfords for a Aircon service. This turned out to be little more than connect a canister and pump up to pressure.

 

Now my aircon is not working and the cooling fan is running flat out.

 

Lee

[Fred Duck]

I included a typo in my reply in that it's the aircon pressure sensor, not valve. It detects a drop in aircon gas pressure and puts the fans into safety mode ie. running all the time. In my case, it was the sensor itself that was faulty and leaked the aircon gas (VCDS picks this up). If your aircon was working fine before it was 'serviced' and it's not now, I'd suggest that either the 'service' hasn't worked or the increase in pressure has caused the sensor (or something else) to fail leaking the gas. Either way, if there's no gas pressure the fans will run all the time. 

 

FD 

[meaty101]

Well I'm a bit confused regarding constantly running fans/low gas. My A/C wasn't blowing cold when i bought the car. A regas sorted it for a short while but eventually stopped again. A scan revealed low refidgerant level and a leak was traced to the condensor. It's now sorted after quite a bit of cash but my fans weren't running at all. So not sure why the fans on your car are running.

[SuperbTWM]

2 hours ago, logiclee said:

 

 

Interesting.

 

My Aircon was working fine, but stupidly I called in at Halfords for a Aircon service. This turned out to be little more than connect a canister and pump up to pressure.

 

Now my aircon is not working and the cooling fan is running flat out.

 

Lee

 

Go back to Halfords and get your money back for a start, then get them to reimburse you for a 'proper' air con service where they will have to suck the the refrigerant out and put the correct amount in

[meaty101]

And never ever go back to Halfords again!! ( unless you need a tool on a Sunday to finish a job when everywhere else is closed!! )

[logiclee]

12 hours ago, SuperbTWM said:

 

Go back to Halfords and get your money back for a start, then get them to reimburse you for a 'proper' air con service where they will have to suck the the refrigerant out and put the correct amount in

 

Don't worry I intend to but can't get back until Friday. I've already spoken to the manager.

 

Shark Performance do all my maintenance and repairs but I mistakenly thought even Halfords couldn't mess up doing a refrigerant top up.

 

I'm also going to ask how they stand legally as you can buy these top up kits and use them yourself but if you are a business and messing with Refrigerant you need certified personnel and the correct equipment. 

 

Lee

[SuperbTWM]

7 hours ago, logiclee said:

I'm also going to ask how they stand legally as you can buy these top up kits and use them yourself but if you are a business and messing with Refrigerant you need certified personnel and the correct equipment. 

 

 

They probably get round it because they are buying it off the shelf just like you would do yourself and they are just 'fitting it' for you, rather than actually having the refrigerant stored on a commercial scale.

 

Either way, its still a bodge, they should have one of those idiot proof machines that does it all for you.

 

[logiclee]

Well it turns out Halford's had not got a good seal on the valve when they connected their canister so had actually let refrigerant escape. So the pressure sensor was sensing low pressure and hence why the fan was running at full speed.

 

It's now been done correctly and all OK.

 

We have a HVAC specialist company at work and I asked their thoughts. In their opinion Halfords are breaking the law using store personnel to carry out "DIY" work on refrigerant systems in the car park. The law is clear that businesses working on refrigerant systems should have the correct accreditation and have engineers trained and certified to the correct standard.

Not only did the Halfords muppet mess my aircon up but released refrigerant to atmosphere which the regs were introduced to prevent.

 

Lee

Edited 2 June, 2017 by logiclee

[Tezza2020]

Hi. I have a 2011 Octavia combi 1.6 tdi and the cooling fan comes on when the engine is cold, and stays on for a while, and this is causing vibration through the steering wheel.

 

I've just changed the coolant temperature sensor, as it was suggested that it could be that, but the issue is still there.

 

So after reading this. I was wondering if it could be that! 

 

If anyone could offer any advice, it would be much appreciated.  I've also looked on the net about changing this yourself and it seems you can, but I'd like to know for sure if that's true or not. 

 

Many thanks

[J.R.]

On 31/05/2017 at 20:41, Fred Duck said:

I included a typo in my reply in that it's the aircon pressure sensor, not valve. It detects a drop in aircon gas pressure and puts the fans into safety mode ie. running all the time. In my case, it was the sensor itself that was faulty and leaked the aircon gas (VCDS picks this up). If your aircon was working fine before it was 'serviced' and it's not now, I'd suggest that either the 'service' hasn't worked or the increase in pressure has caused the sensor (or something else) to fail leaking the gas. Either way, if there's no gas pressure the fans will run all the time. 

 

FD 

 

Been regassing my aircon this afternoon, my fans were not running when the aircon was switched in because the low refrigerant level meant the high side was not getting upi to pressure.

 

Unless your cars have some wacky system what you describe is contrary to the normal operating cycle of the airconditioning system.

 

Aircon off low & high side pressure equal, today at 24°c a fully charged system would be around 5 bar, sict aircon on and temp set to low, interior fan speed high and the high side pressure will drop to around 2 bar and the high side pressure (where the pressure sensor is) will climb slowly to 10 bar (vehicle at standstill no airflow through condensor) at which point the fans will cut in and it will drop to 7 bar if everything is working fine.

 

My pressure was low and the high side was not climbing hence the fans not running, on this and both my Octavias the aircon would only operate the fans when it had the correct refrigerant temperature and pumping correctly, I have had the pressure switches fail and also the system having no pressure and in neither case would the fans operate, its not logical, the only aircon failure that could explain it is the pressure sensor giving an incorrect high reading.

 

Glad to be proved wrong because I am stll learning every day about aircon and these vehicles.

[Zafirov]

On 08/04/2020 at 17:31, Tezza2020 said:

Hi. I have a 2011 Octavia combi 1.6 tdi and the cooling fan comes on when the engine is cold, and stays on for a while, and this is causing vibration through the steering wheel.

 

I've just changed the coolant temperature sensor, as it was suggested that it could be that, but the issue is still there.

 

So after reading this. I was wondering if it could be that! 

 

If anyone could offer any advice, it would be much appreciated.  I've also looked on the net about changing this yourself and it seems you can, but I'd like to know for sure if that's true or not. 

 

Many thanks

Hi there.  Did you solve this?

I have the same problem on my one,  same year same engine. 

Thanks