Notices
Bentley From the original 3 Litre to the current Continental GT and Mulsanne

Continental W12 cooling fans issue

 
  #1  
Old 04-17-2019, 12:42 PM
Registered User
Thread Starter
Join Date: Apr 2019
Location: Canterbury
Age: 49
Posts: 4
Rep Power: 0
MCS Elec is an unknown quantity at this point
Smile Continental W12 cooling fans issue

Hi all, Before I go and start spending a fortune on parts I just wanted to put my problem out there, to see of any one had come arcoss it.
My 2005 GT has no cooling fans working, or sometimes one very very slowly. I have put it on VCDS and there are No faults related to cooling system and when I run the fans through VCDS they still either run slow slow or not at all (rocking) and still no fault code. The car is new to me and there is nothing in the History about cooling issues. My air con needs a re-gas I know but I can drive around all day. But hit slow traffic and the gauge goes to red quickly and I have to find some open road to cool her off.

Any thoughts or advice would be gratefully received (as long as it is not "sell Her" as I am in LOVE).

Thank you. mcs elec
 
  #2  
Old 04-18-2019, 02:01 PM
BWings's Avatar
Registered User
Join Date: Mar 2018
Location: Arizona
Posts: 238
Rep Power: 0
BWings is an unknown quantity at this point
Originally Posted by MCS Elec View Post
Hi all, Before I go and start spending a fortune on parts I just wanted to put my problem out there, to see of any one had come arcoss it.
My 2005 GT has no cooling fans working, or sometimes one very very slowly. I have put it on VCDS and there are No faults related to cooling system and when I run the fans through VCDS they still either run slow slow or not at all (rocking) and still no fault code. The car is new to me and there is nothing in the History about cooling issues. My air con needs a re-gas I know but I can drive around all day. But hit slow traffic and the gauge goes to red quickly and I have to find some open road to cool her off.

Any thoughts or advice would be gratefully received (as long as it is not "sell Her" as I am in LOVE).

Thank you. mcs elec
Hello - These fan motors are high draw (30/40 amps @ full speed). Depending on how much they've been used in almost 15 years now (2005MY), and how much "elements" they've been exposed to, it might be that they're shot. If you can get to the fan pigtail, apply 12v directly to the fans, see if they still run slowly. If so, the fans are gone.

If they suddenly breathe life, then you'll need to look upstream. There will be a fan control module next in line. It is nothing more than a digital (sophisticated) relay and pulse rheostat. On the low voltage side it is usually 5v feeding the relays which switch 12v (high amp and heavy wire) to the fans. The ECU sends pulses on the 5v side at variable frequencies to produce a fan speed measured as a % of full speed. These fan control modules are transistorized, they get hot and burn up, so the FCM does get tired and "goes south".

Either of the above reasons could account for the continuously slow fan speed. A third possibility is grounding. If the earth side of the circuit has lost integrity, then essentially could end up with the same high resistance outcome.

As long as the ECU is producing the 5v pulses according to its MAP, and the ECT remains within an expected range, then there will be no codes shown in VCDS. I'll guess this problem has arisen while ambient air temps have remained cool. If, however, you reach Ambients more in the 25*C range and above, the ECT will cross a threshold and set a CEL.

My (wild) guess is FCM.
 

Last edited by BWings; 04-19-2019 at 07:37 AM.
  #3  
Old 04-18-2019, 02:10 PM
BWings's Avatar
Registered User
Join Date: Mar 2018
Location: Arizona
Posts: 238
Rep Power: 0
BWings is an unknown quantity at this point
The fan control modules (one for each fan) are the silver boxes with the cooling fins. Your cooling fans should look like these. I believe Bentley used this same cooling system on 2004 to at least 2010:

 

Last edited by BWings; 04-18-2019 at 05:11 PM.
  #4  
Old 04-18-2019, 03:41 PM
Registered User
Thread Starter
Join Date: Apr 2019
Location: Canterbury
Age: 49
Posts: 4
Rep Power: 0
MCS Elec is an unknown quantity at this point
Thank you so much for the information. I think it will be really helpful. I think I can see one supply to a Fan from up top.
Do you a standard PWM tester might be able to check out the FCM if I give I it 12v on the large wires 60amp supply and then use the PWM to give it 5v PWM .

I saw elsewhere that some of the Audi fan controllers are the same and interchangeable. Have you come across that?

Thanks again really helpful info.
 
  #5  
Old 04-18-2019, 04:50 PM
Registered User
Join Date: Oct 2015
Age: 45
Posts: 169
Rep Power: 10
TeamJones1962 is on a distinguished road
Hope this can help also.

 
  #6  
Old 04-18-2019, 04:50 PM
BWings's Avatar
Registered User
Join Date: Mar 2018
Location: Arizona
Posts: 238
Rep Power: 0
BWings is an unknown quantity at this point
Originally Posted by MCS Elec View Post
Thank you so much for the information. I think it will be really helpful. I think I can see one supply to a Fan from up top.
Do you a standard PWM tester might be able to check out the FCM if I give I it 12v on the large wires 60amp supply and then use the PWM to give it 5v PWM .

I saw elsewhere that some of the Audi fan controllers are the same and interchangeable. Have you come across that?

Thanks again really helpful info.
I would caution you STRONGLY not to "ping" the 5v. I am not sure here, but for a lot of these same systems the signal is actually a ground and not a +5v. In other words, the + supply is permanent, and the ECU signal completes a ground; therefore, you don't want to be pinging that signal on its earth side with a +v. The easiest half test of this circuit is just unplug at the FCM, bypass it, then feed +12V directly onto the fan motor leads for a short moment. If the fan runs full speed (like it is NOT doing now), then the fans are good. If you can verify the earth is good (it is often the closest/shortest grounding lug in the engine compartment), it leaves the FCM as the culprit.

On the low voltage signals, I have found bad wires on other model cars, but if the LV signal failed there would be a fault code set.

Regards the Audi crossover, cannot say for sure, but 99% sure the Audi or VW Phaeton FCMs are going to be crossovers.
 
  #7  
Old 04-18-2019, 04:58 PM
BWings's Avatar
Registered User
Join Date: Mar 2018
Location: Arizona
Posts: 238
Rep Power: 0
BWings is an unknown quantity at this point
Originally Posted by TeamJones1962 View Post
Hope this can help also.

https://youtu.be/A3d5mOuXMso
Wow we posted at exactly the same time! And a good find! Well done!!
 
  #8  
Old 04-18-2019, 06:13 PM
Registered User
Join Date: Oct 2015
Age: 45
Posts: 169
Rep Power: 10
TeamJones1962 is on a distinguished road
Originally Posted by BWings View Post
Wow we posted at exactly the same time! And a good find! Well done!!
Just trying to help out when I can! I just need to sell this 750 so I can get some more goodies for Jade!!
 
  #9  
Old 04-18-2019, 06:17 PM
BWings's Avatar
Registered User
Join Date: Mar 2018
Location: Arizona
Posts: 238
Rep Power: 0
BWings is an unknown quantity at this point
If you want to take care of a quick check that is free - the two grounds for the fans are found on a single ground lug. They are G00081 (fan 1) and G00082 (fan 2). You'll have to hunt for the lug. The ground wires are brown and this diagram is for a RHD. Make sure you have a clean tight connection with wires in good condition.

 
  #10  
Old 04-19-2019, 09:24 AM
Registered User
Thread Starter
Join Date: Apr 2019
Location: Canterbury
Age: 49
Posts: 4
Rep Power: 0
MCS Elec is an unknown quantity at this point
Originally Posted by TeamJones1962 View Post
Hope this can help also.

https://youtu.be/A3d5mOuXMso
Thank you so much for the Video, I am formulating a plan and I will keep the post updated .
Thanks again
 
  #11  
Old 04-19-2019, 09:40 AM
Registered User
Thread Starter
Join Date: Apr 2019
Location: Canterbury
Age: 49
Posts: 4
Rep Power: 0
MCS Elec is an unknown quantity at this point
Plan so far

Bwings, amazing info , thank you again . I have a plan now, I won’t test the FCM units, I have however found two working S/H Phaeton units for very little £££ so I have ordered and next weekend I will strip and test fans and one way or another I hope I will have all the parts to sort the problem I Checked Earths and all seems secure and corrosion free. I will of course update to the post when job is done. Thanks for the help , invaluable. MCS Elec
 
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Brady Miklos
Cayenne Turbo
3
07-19-2016 11:51 AM
yvesvidal
997
4
01-06-2016 05:47 PM
Abby997TT
997 Turbo / GT2
11
10-20-2010 08:06 PM


Thread Tools
Search this Thread
Rate This Thread
Rate This Thread:

Quick Reply: Continental W12 cooling fans issue


Join 6SpeedOnline
Visit our Sponsors

Contact Us - About Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.