Cooling fans "running on" after switch-off

[phil1380]

Hello there.

 

I'm new to Skoda ownership and have recently acquired a 2012 Yeti SE 170 4x4.  

 

A couple of times now after a decent run the cooling fans have "run on" after turning the engine off - I would expect them to switch themselves off after a short period of time (assuming the fan switch is mounted on or close to the radiator and therefore cooled down by the fan) but they don't seem to have done so after say 5 mins post engine off.   

 

In order to get the fans to turn off a quick restart of the engine and a switch off again seems to shut the fans off.

 

Is this normal behaviour or something warranting further investigation ??

 

Thanks in advance.

 

Phil.

 

 

[Russ77]

Is it a diesel?  If so it's likely there was an active DPF regen running when you switched the engine off.

 

The DPF is heated up to around 600c for this process so the fans continue to run to dissipate the heat.

[phil1380]

Just now, Russ77 said:

Is it a diesel?  If so it's likely there was an active DPF regen running when you switched the engine off.

 

The DPF is heated up to around 600c for this process so the fans continue to run to dissipate the heat.

Yes it's diesel.

 

Ok, that makes sense.

 

Presumably the fans will shut off when the regen is done ??

 

Phil.

[mrgf]

Many cars have electric fans over-run by intention so don't be too alarmed by this. If however, it still runs say, ten-fifteen mins later, there could be an issue. Some people (Fabia thread) have had to disconnect the battery in order to stop fans continually spinning, which is a pain. 

It appeared also, that the issue started after very hard rainfall. It might have ben the electrics kind of "Bridging" due to the wet, making the fans run so drying/cleaning and insulation the terminals might solver this but I cannot remember if the issue got rectified, I just remember a fee discussions a few years ago. (Mr Crow, I think, was one of the sufferers).

[Russ77]

6 minutes ago, phil1380 said:

Yes it's diesel.

 

Ok, that makes sense.

 

Presumably the fans will shut off when the regen is done ??

 

Phil.

Not necessarily........  When you turn the engine off, the regen stops, the fans are only there to cool things down.  If the regen isn't complete then it'll try again when the regen criteria is met again.

 

I've got a bluetooth adapter that plugs into the diagnostic port and an app called "VAG DPF", what I've witnessed on my own car is when the soot level reaches 100%, the regen process begins (at this point the revs sit at around 1K when idling).  Driving normally the DPF heats up to around 600c and the soot level drops off until it gets to around 25%-30% and the DPF process is completed (at an estimate this takes around 15-20mins of steady driving, keeping the engine under a reasonable amount of load rather than just thrashing the nuts off it).

What I've seen if this process is interrupted........  let's say the soot level only gets to 75% when you switch off......  it tends to wait until it gets back up to around 90% then kicks off the regen process again.

[gumdrop]

DPF regen. interrupted, so the fan was trying to keep an extra engine cool.

[silver1011]

Some bedtime reading here for you...

 

 

[muddyjim]

It's also in the handbook:

 

Quote

■ To assist the combustion process of the soot particles, we recommend that regularly
driving over short distances should be avoided.
■ Using diesel fuel with an increased sulphur content can considerably reduce the
life of the diesel particle filter. A ŠKODA service partner will be able to tell you
which countries use diesel fuel with a high sulphur content.
■ If the engine is turned off during the filter cleaning process or shortly afterwards,
the cooling fan may turn on automatically for a few minutes.

 

Edited 17 October, 2019 by muddyjim