A7 C7 3.0 Tfsi, WIERD COOLING FANS ISSUE, Need Advice

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Zoaib_H

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As per the title - my radiator cooling fans dont work as they should and I cant figure out why. Generally speaking whenever the AC is off, the fans dont spin at all, and I have see the temperatures rise and rise. It has on an occasion led to damage - new Gearbox oil cooler, and even caused a blown head gasket due to overheating. I used VCDS - No codes related to anything about cooling or fans etc

I used OBDEleven and noticed temps hitting 100 and still the fans were not spinning more than 10% speed. The screenshots are attached.

whatsapp_image_2021_02_22_at_12_10_18_am_919bfda4a58d145be943f226de320bf7b0140557.jpeg


AC Off and at 96'C only one fan runs fairly slow

whatsapp_image_2021_02_22_at_12_10_19_am_4136335dfbdea163f9c7df44f1478c6b74c633de.jpeg


AC Off and at 99'C only one fan runs fairly slow also, I know from experience it will only climb up to 100+ and the fans wont kick in

whatsapp_image_2021_02_22_at_12_11_38_am_7d8ec9dd2890c06fe4a7578fc630d28f2e3073af.jpeg


A/C On - both fans run at medium speed - provided some cooling and temps started lowering...

The weird thing is, despite the fan activation above, When the A/C is switched off, only one fan spins and that too at slow speed. However when the AC is on, they spin at around 40-50% speed.

I then ran an output test on the fans, and they ramped up to 100% speed - this was a surprise to me as I have never seen them work so fast.

So I am now confused as I thought the issue was with my Cooling fan control modules, but in the output test they worked... Could it be something else?

(For reference the Thermostat and water pump were switched out for brand new 6 months ago)

can anyone advise?
 
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Uwe

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I used OBDEleven and noticed temps hitting 100 and still the fans were not spinning more than 10% speed.
100°C is not hot enough to cause any problem. That's normal operating temperature.

If you're going to post data from OBDEleven rather than VCDS, I suggest taking your questions to an OBDEleven forum rather than the Ross-Tech forum.

-Uwe-
 

Zoaib_H

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Thanks for the reply Uwe. I am an avid VCDS user, I just so happened to be in the car at the time the temps were rising and I didnt have my laptop at hand, so I used OBDEleven purely out of convenience.

I do get your point though, I will remove the OBDEleven screenshots and referrences and update my post

The concern I have is, temps rise and will continue going past 110°C if I dont turn off the engine or start driving fast enough for air flow to cool the radiator... The Fans arent kicking in as they should..
the point of confusion for me is, are the Fan control modules are the issue (even though the Output test seemed fine), or is there another element to it which is not triggering my fans to kick in...

anyone know?
 

Zoaib_H

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Uh oh, this is embarrassing. I cant figure out how to edit my first post :facepalm:

If anyone can direct me to how to do so I would really appreciate it. Im not trying to break any rules or cause any stirs on the forum, just trying to benefit and contribute
 

Uwe

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I cant figure out how to edit my first post
There is a time limit on users' ability to edit. Just post your VCDS data below.

-Uwe-
 

NZDubNurd

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The Fans arent kicking in as they should..
Based on what? You need to know the logic programmed in, to decide if they are working correctly or not. The service manual may have that information.

they may not be designed to work how you think/want them to, and possibly not even fr what is best for engine life - emissions and economy are prioritized over longevity and reliability... I'm not sure which works out better for the planet!

Also, what coolant temp sensor is that reading from? (I assume engine/head) The engine can be a different temp to the radiator return, and it's not unusual for the ECU to control fan speed based on the radiator output. There may be multiple coolant temperature sensors.

The Germans have been running engines VERY hot for a long time, and buffering the gauges SO much, that 110C is pretty common, even with a gauge reading "normal" (90C). Some of the Map-controlled systems run 105 or 110C as a normal temp, and electrically heat the thermostat to open it and reduce running temps under heavier loads (that started in the mid-late 90's on some cars)

The ECU *may* be seeing only 90C in the radiator return, so doesn't run the fans yet as there is still cooling capacity remaining. It may be happy to run the engine at 110C under the conditions at the time too - higher running temp reduces fuel consumption and emissions (at least in the short term).
 

Zoaib_H

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based on experience I know the fans wont kick in as they should. Ive logged the temps on vcds and even on the not-so-accurate temp guage on the dash its shown 120 degrees in the past and the fan was not spinning...

with that happening repeatedly I got damage.. head gasket went, the oil cooler went.. my mechanics have fixed the symptoms but never the root cause..


I have been doing a lot more reading now and I am convinced that it is the Fan control module... I might have to change those and observe
 
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