Afterrun fans

[steve2003rs6]

Usually when I switch off the ignition the fans continue to run for a while.
That seems to have stopped working.
VCDS shows 18080 coolant fan 1 open or short to ground p1672-004.
Any advice would be appreciated.

[TechNick]

for you that coolant fan #1 isn't the £1k one of the two

[steve2003rs6]

I bet it will be ?
Thanks technic.

[Shoppinit]

IIRC that's the big 600W fan with the built-in controller.

Use the Vagcom to start and stop the fan first before changing it. It might just be that the conditions aren't calling for the fan to activate.

[steve2003rs6]

Thank you Ben.
Will give it a go.

[Shoppinit]

Output tests is what it's called in VCDS IIRC.

[Mɐʇʇ]

IIRC that's the big 600W fan with the built-in controller.

Use the Vagcom to start and stop the fan first before changing it. It might just be that the conditions aren't calling for the fan to activate.

Do you know anything about the controller? What does it do?

[Shoppinit]

I believe it's a simple PWM controller to control the fan speed. The ECU sends a PWM signal and the controller converts the low voltage pulses into high current ones to get the fan to rotate, probably using MOSFETs or similar. I bet they are easy to fix / replace with a DIY PWM amplifier.

I'd check with a scope on the input to the controller. *Might* be CAN message instead of PWM, but I doubt it. Need to look at the electrical diagrams and I don't have Elsa at the mo.

[Mɐʇʇ]

Yeah, you see my line of thought there, although I don’t plan on “doing” unless the need arises

[steve2003rs6]

Just been doing some research. I came across some info that said if the fans continue to run when you switch off the car, this is a fault which can be caused by corrosion of the fans.

Since I bought the car in 2012. When I start the car you can hear the fans winding up. After a run when you turn the ignition off the fans continued to run for a while.
I thought this was normal.

But having read that it may have been a fault I am now unsure how the fans should operate.
Please advise

[TechNick]

Just been doing some research. I came across some info that said if the fans continue to run when you switch off the car, this is a fault which can be caused by corrosion of the fans.

Since I bought the car in 2012. When I start the car you can hear the fans winding up. After a run when you turn the ignition off the fans continued to run for a while.
I thought this was normal.

But having read that it may have been a fault I am now unsure how the fans should operate.
Please advise

Can't comment with any authority (as knowledge / memory on this is sketchy at best), but doesn't one of the fans come on with the A/C?
May possibly be another basic test that can be carried out without VCDS, oscilloscope, etc.

[steve2003rs6]

Hi Technick. Yes mate the a/c on does effect the fan. Well that’s what I came across after reading some stuff on it today.
Also :
Poss 5 amp fuse
Poss fan module in the fan
Poss faulty temp sensor.
From what I gathered, corrosion is also a possibility.

I need to spend a bit of time on it with VCDS.

I also read that it is normal for the fans to run for a short while after the ignition is turned off.

[Shoppinit]

The ECU controls the fans. The AC unit can ask the ECU to activate the fans (so fan is likely to be on if the AC is on).

Also, the fans will come on if the coolant temp is above 98 degrees.

The fans will stay on (after run) if the coolant and/or oil temps are high when you switch off the engine.

First thing to do is the output test to see if the fans spin up when requested with the Vagcom.

If not, then you can look into why.

I don't buy the corrosion thing. Or rather, contact corrosion could apply to any electrical fault.

[steve2003rs6]

Thank you Ben.
Onto it soon.

[steve2003rs6]

Just for other members info.
Using VCDS test run performed on both fans.
Fan 2 ran on test
Fan 1 didn’t
Now to investigate why.
Will update as we go.