Revisiting a topic: After Run Fans

**ben916** · February 19th, 2011, 04:51

History:
I purchased in Feb 2010 with 36k miles on her and I knew right off the rotors needed replacement.
One topic that came up early, probably within a month or so of ownership, was the after run fans.

After any type of run, spirited or daily driver, 116F or 50F, the after run fans NEVER come on.
They do come on while the car is running and the A/C is on. No other time!

Ideas?

This was brought to light as Wade's (born2be) fans were running full bore for like 5 minutes, even when it was started and backed up 5 feet.
Hoehn Audi, from what he told me, has diagnosed his T-stat as toast.
John's (audi5000csqt) car run for maybe a minute after shut down, IIRC.

What does everyone else's do?
If this is an issue, where should I start looking?
Fuses?
Electrical Connections?
Fan?

Thanks!

EDIT:
the oil temp gauge is never over 200F
the water temp gauge is usually in the middle

**hahnmgh63** · February 19th, 2011, 04:55

Have only noticed mine come on a couple of times in the last 6 years other than when the Climate Control switch was in Auto, normally I run it is Econ. I believe it should almost always run when in Auto?

**Elevens** · February 19th, 2011, 05:16

Mine always come on after I shut down here in Florida. I know this because it squeaks after it comes on. Probably letting me know that the Fan bearings are going. At any rate I believe above a certain temperature the After Run coolant fan should come on to help cool down those Turbo's. If the Fan works, I would say check the Thermo-switch which turns that fan on and off.......

**ben916** · February 19th, 2011, 05:52

Originally Posted by Elevens

Mine always come on after I shut down here in Florida. I know this because it squeaks after it comes on. Probably letting me know that the Fan bearings are going. At any rate I believe above a certain temperature the After Run coolant fan should come on to help cool down those Turbo's. If the Fan works, I would say check the Thermo-switch which turns that fan on and off.......

Can you point me in the direction of where that would be?
Schematic?
Drawing?

**Elevens** · February 19th, 2011, 06:16

Originally Posted by ben916

Can you point me in the direction of where that would be?
Schematic?
Drawing?

Ben, I've had this car for about a year now and I haven't really touched it yet (asides from mods). So where the Switch is located I don't know and I can't really help you with any schematics. Pat is probably your best bet at this point. He'll probably point you in the right direction. When I get a chance I will have to look into mine also, because my fan sounds like it on its way out making all kinds of noises when it comes on........

**hahnmgh63** · February 19th, 2011, 06:57

Fans
Two suction fans connected in parallel
(600 W and 300 W) are used to provide
cooling air. The fan control modules are
actuated by way of the engine control
module as a function of load.
The control module for the 600 W fan is
integrated directly into the fan motor,
whereas the 300 W fan has a separate
control module/output stage. Different
conditions apply to actuation of the two
fans.

1. The fan request is transmitted by the air
conditioner operating module via the
CAN-bus to the engine control module,
where it is then relayed directly to the
fans.
2. In normal engine operation or at idle the
fans are controlled as a function of
engine and ambient temperature.
Maximum selection is made between
the air conditioner and engine
temperature.
3. Triggering and duration of fan run-on after
switching the engine off are governed by
three different criteria:
- Average fuel consumption > 7 ml/s and
engine temperature > 220ºF when
engine is switched off
- Measured engine temperature greater
than 220ºF and ambient temperature
greater than 32ºF
- On switching off the engine, oil
temperature greater than 200ºF

If the fan control modules do not
receive any information from the
engine control module, the fans
switch to emergency operation and
this is recorded in the fault memory.
Checking fan operation with the
engine running will not guarantee
that the fans will respond in run-on
mode. A separate check must
always be made following repairs.
Use the VAS 5051 Scan Tool for final
control module diagnosis.

**ben916** · February 19th, 2011, 07:22

Originally Posted by hahnmgh63

Fans
Two suction fans connected in parallel
(600 W and 300 W) are used to provide
cooling air. The fan control modules are
actuated by way of the engine control
module as a function of load.
The control module for the 600 W fan is
integrated directly into the fan motor,
whereas the 300 W fan has a separate
control module/output stage. Different
conditions apply to actuation of the two
fans.

1. The fan request is transmitted by the air
conditioner operating module via the
CAN-bus to the engine control module,
where it is then relayed directly to the
fans.
2. In normal engine operation or at idle the
fans are controlled as a function of
engine and ambient temperature.
Maximum selection is made between
the air conditioner and engine
temperature.
3. Triggering and duration of fan run-on after
switching the engine off are governed by
three different criteria:
- Average fuel consumption > 7 ml/s and
engine temperature > 220ºF when
engine is switched off
- Measured engine temperature greater
than 220ºF and ambient temperature
greater than 32ºF
- On switching off the engine, oil
temperature greater than 200ºF

If the fan control modules do not
receive any information from the
engine control module, the fans
switch to emergency operation and
this is recorded in the fault memory.
Checking fan operation with the
engine running will not guarantee
that the fans will respond in run-on
mode. A separate check must
always be made following repairs.
Use the VAS 5051 Scan Tool for final
control module diagnosis.

I will ask Mike at PureMS to VAG-Com it, tomorrow after the poker run

**Elevens** · February 19th, 2011, 14:16

Wow! A little more complicated than I thought Huh.......

**hahnmgh63** · February 19th, 2011, 15:42

Yea, more complicated than I thought too with the ECU making some of the decisions, not just raw data. Sounds like the use of Vagcom is a must to start with. I'm in a little cooler climate and I always idle my car down or drive easy for the last couple of miles, at least when I'm coming home, and always pop the hood in the garage to let it cool faster and not bake the rubber hoses so I can understand why I've only heard mine run a couple of times in 6 years, and I'm pretty sure it was in the summer both times.

**Aronis** · February 19th, 2011, 19:27

The after run fans on my car were stuck on last year! I had to reset something with VAG-Com ( I don't recall the specifics) and ended up with a temperature sensor problem which was located on the fire wall. That was fixed and it's been fine.

I do have a question about those fans though. Don't they just blow air at the radiator and engine without any fluid circulating?

People have written about Turbo Timers which keep the entire engine running for a few minutes after you walk away with the keys in hand. That's totally different, right?

Mike

**JSRS6** · February 19th, 2011, 20:20

I think the after run fans work in concert with the after run pump maybe? So there should be fluid running through also. But I could be wrong...

**Aronis** · February 20th, 2011, 00:55

I figured that, but then what would be the need for a Turbo Timer, couldn't one just recode the ECU to run the after run fan at a lower temperature?

Mike

**ttboost** · February 20th, 2011, 01:31

Turbo timer is just to keep idling the engine (after engine shutoff) to cool down the turbos, to prevent "coking" in the turbos. Nothing at all to do with engine cool down.

**ben916** · February 24th, 2011, 03:26

What about this part (not necessarily this EXACT part, but you get the idea...)?
This is for the water pump.
http://jhmotorsports.com/shop/catalo...1ce17c33f17a6c

This one is for the fans "Resolves many fan issues or fans that don't turn on"
http://jhmotorsports.com/shop/catalo...1ce17c33f17a6c

**hahnmgh63** · February 24th, 2011, 03:30

Just like the link I posted under the brake thread. You must click on it then close it, then re-open it again for it to work? Not sure if it would really increase the life of the Turbos if your using quality oils, the pump wearing out early would be a PIA to change.

**ben916** · February 24th, 2011, 03:36

updated post 14

**hahnmgh63** · February 24th, 2011, 03:40

For a $20 part it wouldn't hurt to try the aux fan switch that Ben just posted. That is the lower right side radiator hose they are talking about. Easier to access from the bottom with the belly pan off.

**ben916** · February 24th, 2011, 03:42

Originally Posted by hahnmgh63

For a $20 part it wouldn't hurt to try the aux fan switch that Ben just posted. That is the lower right side radiator hose they are talking about. Easier to access from the bottom with the belly pan off.

Thank you for letting me know where I should look...
I will check it out next time

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