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AlanCoke
Audi Nut



Joined: Jun 20, 2007
Posts: 55
Location: West Yorkshire, England

PostPosted: Wed Jun 20, 2007 6:35 am Reply with quote Back to top

Hi,

I have just joined the Audi club after purchasing an A4 3.0 Litre Quattro Automatic / Tiptronic from a car auction; the car is a Feb 02 model with just 29,000 miles on the clock.

As I drove the car home the temp stayed at bang on 90 Degrees Centigrade until I hit a traffic jam. At this point the temperature started to creep up until the alarm came on the dashboard letting me know the coolant temperature was high. As the traffic cleared the temperature came back down to 90 Degrees Centigrade with no issues for the rest of my trip.

When I arrived home I opened the bonnet and left the engine running. As the temperature started to creep up I expected one or both of the electric fans to come on but neither of them did.

The coolant level remains constant and shows no signs of a leak.

I am an electrician but unfortunately the Haynes manual for this model is not due out for around one month so I can't test because I don't have any electrical diagrams. I have checked the 15A fan fuse (thinks that's the right one) but I could do with some advice and some electrical diagrams.

Any help or advice would be appreciated.

Alan.
 
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Cullam3n
UltraUser



Joined: Feb 16, 2007
Posts: 1598
Location: West Suffolk

PostPosted: Wed Jun 20, 2007 6:58 am Reply with quote Back to top

Hello and welcome to the forums!

Might want to try the fan sensor/switch. The sensor will sit somewhere along the bottom of the rad (mine's on the driver side) and will most likely be 3 pin. If you jump two of the pins together (1 and 2 for low speed, 2 and 3 for high) the fans should come on. If they don't, then you have an electrical fault. If it does, then the sensor might be bad.

_________________

1992 - B4 80 - 2.8L V6 12v - Quattro - Saloon - 220,000+ mi
AOC::: 1337
 
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AlanCoke
Audi Nut



Joined: Jun 20, 2007
Posts: 55
Location: West Yorkshire, England

PostPosted: Wed Jun 20, 2007 6:42 pm Reply with quote Back to top

Thanks for the info.

I have looked at the radiator and I can't find a temp sensor / switch on the bottom edge of the radiator as you have described. The only sensor that appears to be attached to the radiator is one near the top (NS), this is held on by two bolts and it has a yellow plug attached to it, There also appears to be something near the top (OS) with a yellow plug but without removing various parts I can't confirm what it is.

Because your car is a 2.8 and my car is the 3 Litre I suspect Audi have made a few subtle changes.

If anyone can assist with this problem it would help me avoid the Audi dealership hourly rates.

Thanks for your reply,

Alan.
 
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AlanCoke
Audi Nut



Joined: Jun 20, 2007
Posts: 55
Location: West Yorkshire, England

PostPosted: Wed Jun 20, 2007 8:14 pm Reply with quote Back to top

Bit of an update on this issue.

I have traced both fan cables back to an Aluminium finned unit that sits just behind the top of the radiator, this appears to be either a pair of solid state relays or it could something a little more sophisticated like a variable fan speed controller. It has the following connections:

Orange - Fan 1 +
Yellow - Fan 2 +
Purple - Fan 1 –
Red - 12 VDC supply
Brown? - 0 VDC supply
Blue - Could be a 12 VDC fan run signal or a variable signal
Green - Fan 2 –
Black? - Could be a 12 VDC fan run signal or a variable signal

Both fans actually work if you put 12 VDC onto the Fan + side.

Unit details:

Valeo

MH 1052
8734 79G A

Beuffer
01-333-F
00107998

System HKR
STG 600W
BEO 959 501D

Any ideas on how to test this unit?

I don’t have the B***S to put a 12 VDC signal onto the signal connectors in case this comes directly from the ECU.

Regards,

Alan.
 
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cq20v
Site ADMIN
Site ADMIN



Joined: Jan 20, 2003
Posts: 13250
Location: West Midlands

PostPosted: Wed Jun 20, 2007 9:58 pm Reply with quote Back to top

Like you say, sounds like some kind of fan speed controller and by the sounds of it, it's knackered! Sad

_________________
2007 Skoda Fabia vRS SE
1995 80 quattro Sold, died, sold
1994 80 \"Project Titan\" - Now deceased
1993 S2 Coupe - Sold (gutted)
1989 CQ20V - Sold
1986 Coupe GT - Deceased
1985 Coupe GT - Deceased  
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NineNails
Site Moderator
Site Moderator



Joined: Jun 01, 2003
Posts: 3351
Location: North Wales

PostPosted: Wed Jun 20, 2007 11:33 pm Reply with quote Back to top

Could still be the outlet coolant temp sender. This is definately on the bottom radiator hose connection, next to the coolant drain plug. I would think you'll have to remove the belly pan to get at/see it. DON'T go randomly shoving 12v round the place, it can get expensive Shocked
Si.

_________________
2000/w Audi A4 1.8T quattro Sport
Proud sponsor of the snack food industry.
 
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AlanCoke
Audi Nut



Joined: Jun 20, 2007
Posts: 55
Location: West Yorkshire, England

PostPosted: Fri Jun 22, 2007 8:16 am Reply with quote Back to top

Hi all, here is an update.

This problem is now sorted, I spoke off the record to an Audi electrician and he agreed that the tests carried out pointed to the fan speed controller being at fault. Quick trip to Bolton Audi to pick one up (only one in the country), 30 Minutes to fit and both fans burst into life. Speed of the fans now adjust with coolant temperature.

Thanks for your comments and I hope this info helps other owners.

Ps, the cars fantastic!

Alan.
 
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Cullam3n
UltraUser



Joined: Feb 16, 2007
Posts: 1598
Location: West Suffolk

PostPosted: Fri Jun 22, 2007 4:54 pm Reply with quote Back to top

They sure are, have a friend that has a US spec b6 A4 3.0v6 Very Happy

_________________

1992 - B4 80 - 2.8L V6 12v - Quattro - Saloon - 220,000+ mi
AOC::: 1337
 
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cq20v
Site ADMIN
Site ADMIN



Joined: Jan 20, 2003
Posts: 13250
Location: West Midlands

PostPosted: Fri Jun 22, 2007 5:07 pm Reply with quote Back to top

Glad you're all sorted Alan Very Happy

Happy motoring !

_________________
2007 Skoda Fabia vRS SE
1995 80 quattro Sold, died, sold
1994 80 \"Project Titan\" - Now deceased
1993 S2 Coupe - Sold (gutted)
1989 CQ20V - Sold
1986 Coupe GT - Deceased
1985 Coupe GT - Deceased  
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NineNails
Site Moderator
Site Moderator



Joined: Jun 01, 2003
Posts: 3351
Location: North Wales

PostPosted: Fri Jun 22, 2007 5:33 pm Reply with quote Back to top

Thanks for the feedback Wink
Love a happy ending Smile
Si.

_________________
2000/w Audi A4 1.8T quattro Sport
Proud sponsor of the snack food industry.
 
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ukbill69
Newbie
Newbie



Joined: Apr 16, 2015
Posts: 1

PostPosted: Thu Apr 16, 2015 8:27 pm Reply with quote Back to top

I think ive got the same issue,

My mechanic has told me part attached is at fault as fans do not turn on and coolant overheats when idle for some time. I cant seem to find part any where online and my mechanic is finding it hard to find it no cheaper than £215. Any advice would be great.



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AlanCoke
Audi Nut



Joined: Jun 20, 2007
Posts: 55
Location: West Yorkshire, England

PostPosted: Fri Apr 17, 2015 12:21 pm Reply with quote Back to top

Hi,

Yes that's the same sort of unit that I replaced although as far as I can remember (I have has three different cars since the Audi).

It would not surprise me that the unit is £215, as far as I can remember mine was £160 back in 2007 so what with inflation over the last 8 years it seems about right.

Regards,

Alan......
 
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