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Engine cooling and auxiliary fans not turning on

Tiny
STEVEI0742
  • MEMBER
  • 2007 AUDI A6
  • 3.0L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 168,000 MILES
Hi. My engine cooling and auxiliary fans are not coming on when the car is running, I have access to VCDS and I can do the fan test which does make them run so they are mechanically/electrically okay. I have checked every fuse I can find to do with the system and all are okay. I have not checked relays. VCDS shows no fault codes for HVAC at all! I am lost now for what to do next, please help!

Steve.
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Saturday, August 25th, 2018 AT 10:40 AM

10 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,526 POSTS
I would start by checking the relays (1.2). Here is a guide to show you how and the cooling fan wiring diagrams to help you see how the system works with the relay locations below:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Check out the diagrams (below). Please run this test and get back to us.

Cheers, Ken
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Sunday, August 26th, 2018 AT 12:23 PM
Tiny
STEVEI0742
  • MEMBER
  • 3 POSTS
Hi Ken, thanks for the information. Is it possible to email me full size copies of those wiring diagrams? I can only open these to a small size on screen and difficult to view them.

Thanks Steve.
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Monday, August 27th, 2018 AT 12:09 AM
Tiny
STEVEI0742
  • MEMBER
  • 3 POSTS
Hi Ken.

Thanks for the diagrams, I was trying to view them on a laptop but when I clicked on them I only got a small copy about 4x4 in the centre of the screen, I'll have a look at the one's you have just sent shortly. Thanks again.

Steve.
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Monday, August 27th, 2018 AT 10:48 AM
Tiny
CASSIE GAETE
  • MEMBER
  • 12 POSTS
I am having the same issue with my 2006 a6 Quattro 3.2l. All fuses okay. I can hardwire my fans on using the module harness wire. But when I turn my air on or run the car neither fans work.

Confused on relays I can’t find diagrams/locations for the 2006 A6 Quattro 3.2l
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Wednesday, May 26th, 2021 AT 3:03 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,526 POSTS
I would check the fuses first the system is simple it looks like the ECU controls the fans which could be bad, but let's stick with the fuses first. here are the fuses you need to check with a guide to show you how:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Check out the diagrams (below). Let us know what happens and please upload pictures or videos of the problem.
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Friday, May 28th, 2021 AT 11:19 AM
Tiny
CASSIE GAETE
  • MEMBER
  • 12 POSTS
I have checked fuses. But none of those you listed are for the cooling fans? I have power going to my fans. They just don’t turn on. I can put alligator clips with 12v and they spin on high. I’ve swapped modules with a lkq pull still no luck. (Maybe another dud?)

Either way I’d like to 100% rule out relays.
How do I access the relays under the steering wheel? The fuses by the firewall checked out (by the ECU and driver side under the steering wheel).

I check the driver side fuses in the cabin. All were good.

I checked the firewall under the hood fuse boxes. All fuses were good.
2 Relays came back close to being out of spec according to Google (2 70 amp labeled 614 on top driver side firewall)

Both had jumpy resistance readings when under 12v load. From 2-45

Both had.49 and.50 resistance without load.

Is that normal?

This is the last thing I can think of besides another relay under the dash I can’t seem to get to or a module but being it’s getting power im stumped.
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Monday, May 31st, 2021 AT 4:59 PM
Tiny
CASSIE GAETE
  • MEMBER
  • 12 POSTS
Video of fans running well on 12v.

This is a 2006 a6 Quattro 3.2l v6 just in case.
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Monday, May 31st, 2021 AT 5:02 PM
Tiny
CASSIE GAETE
  • MEMBER
  • 12 POSTS
So I checked power coming from the module and there is none. Test light isn’t giving a flicker with car on, car running full A/C or car running full heat. Should I also mention A/C is hot breath now and no longer cold.
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Tuesday, June 1st, 2021 AT 2:00 PM
Tiny
CASSIE GAETE
  • MEMBER
  • 12 POSTS
Wired in a new module. Check this out, (video) lol the car is off. No key in ignition. Plugged in new fan modules and fans instant high speed.

Tried replacing relays (photo). Did nothing even when I pulled the relay out while the fans were running.
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Tuesday, June 1st, 2021 AT 4:44 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,709 POSTS
Hi,

You must have a short to power. If you remove the fuses one at a time, are there any that shut the fans down? I noted that you indicated removal of the relays didn't turn them off and with the key on, there is no power to the module. Apparently, there is power with the key off.

Try removing one fuse at a time to see if there is one that shuts power down to the fan with the key off. If we can determine that, at least we'll have a circuit to start checking for a short to power.

I have to say, the idea that you have power with the key off and no power with the key on may indicate an issue with the ignition switch.

Let us know.

Joe
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Saturday, June 5th, 2021 AT 7:23 PM

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