Second radiator fan purpose

[Steroidas]

Hey guys!

Just wanted to ask for explanation: whats the purpose of the second radiator fan (marked in the photo) and under which circumstances he will kick off?

Asking because i noticed that second one is always off and while clima is on auto mode the large one is only spinning. Thanks for the info!

[Breezy_Pete]

What year was the car built? Do you know if the fan control module is built into the main fan (if it is, the power to that smaller fan will come from the main fan), or is it separate?

On Skodas with separate control module, both fans are usually wired in parallel, so should both run any time fan action is commanded.

 

[Steroidas]

2006 1.9 BJB

[Breezy_Pete]

I think your car will have the fan control module built into the main fan. You can perhaps disconnect the smaller fan and try powering it directly from battery to test if it works?

 

[Steroidas]

So they always have to work in parallel or do thy have different purpose?

Edited 27 June, 2023 by Steroidas

[Breezy_Pete]

I'm not 100% sure on that version of things. Wait for someone with the same age/engine car replies, I think.

A forum post I read some years ago said they should both work at the same time, but I don't know if I could find it again (wasn't this forum).

 

 

[Steroidas]

In the other words how should i know if my fan or control module is faulty and had to be replaced?

[Breezy_Pete]

Test the small fan on its own, as suggested above, as a first step. If that doesn't work you'll know that is a problem.

[Steroidas]

Just now, Breezy_Pete said:

I'm not 100% sure on that version of things. Wait for someone with the same age/engine car replies, I think.

A forum post I read some years ago said they should both work at the same time, but I don't know if I could find it again (wasn't this forum).

 

 

Thank you very much for your input! lets see other opinions

[Breezy_Pete]

I found the description of function that I remembered seeing! 

https://www.briskoda.net/forums/topic/470840-aircon-puzzle-intermittent-cold-output/?do=findComment&comment=5289212

 

[Steroidas]

Okay, so did VCDS output test which is called Coolant fan control circuit 1 ( which is shown in this video ) and i find out that this test should kick out both fans, but in my case only larger one is spinning up..:(

 

[Guest]

@Steroidas

 

Check for a wiring problem.

[Breezy_Pete]

I think the only way to prove that the problem is/isn't the control unit in the main fan is to power the small fan independently after disconnecting it from the big fan.

[Steroidas]

Agree, i think i will do it during inspection. The only question is: what is the percentage what the bigger fan will start to fail soon and is it worth to change the both fans at the same time and forgot about them..

[Breezy_Pete]

If the problem is confirmed as the control unit in the main/big fan then there will be no point in replacing the small one.

[Steroidas]

So the problem was in the main fan controller, as smaller fan connected directly to the battery was spinning. Thank you everyone for the help and suggestions!

[jong123]

isn't the second fan used when the air con is initiated ?

[Steroidas]

2 hours ago, jong123 said:

isn't the second fan used when the air con is initiated ?

Yup the second fan (smaller one) is AC fan. i am not sure if there are any difference between AC and climatronic, but now once the clima is on - both fans are triggered and spinning up

[Breezy_Pete]

@Steroidas does your engine coolant ever get hot enough to trigger fan activity when clima is off? If so, do both fans spin up together in those conditions?