Ansteuerung Kühlerlüfter Audi 2,7 TDI (BPP) mit Standheizung | Posts 16+

Hi,

I'm now relatively certain that the G83 sensor doesn't exist on my engine. I proactively replaced the G62 sensor, but there was no change in behavior.
The e-box on the left-hand side, in the direction of travel, inside the water tank is dry.

I also took a more extensive test drive, with the following results:
Sobald der Motor warm ist und die Klimaanlage an ist, werden beide Lüfter angesteuert und laufen auch. Gleichzeitig sinkt mit steigender Lüfteransteuerung die Kühlwassertemperatur wie erwartet und pegelt sich (im Stand mit erhöhter Drehzahl) bei etwa 93-97° ein . Sobald die Klimaanlage ausgeschaltet wird, geht für beide Lüfter der Ansteuerwert (auf den auch oben schon dargestellten) Wert von 10.3 % zurück und die Lüfter drehen NICHT.Dementsprechend erfolgt auch keine ausreichende Kühlung, die Temperatur steigt. DarauI assume that...
- Fan motors are working properly.
- Coolant pump is working correctly, and the coolant is being circulated adequately.
- Thermostat is okay, the main circuit is activating.
- G62 OK, values seem reasonable.
- Fan fuses are okay.

The question that remains unclear to me is why...
- Without the air conditioning running, the control system does not change, and the motor overheats.
- The trigger value of "10.3%" does not cause the fans to spin.
- Is it correct that this motor only offers a continuously variable fan speed control, and not, for example, a 2-speed setting?
- Is it correct that the control system relies on a pressure sensor in the air conditioning refrigerant circuit, and not on the G62 sensor?
- It can be assumed that the cable connection from the G62 to the MSG is okay, as the value is displayed plausibly in both VCDS and the instrument cluster (and the G62 is a 2-pin sensor).
- Could it be that the messaging system ("MSG") is "crashing," and is there a way to reset it?

Just to reiterate, the only symptom is the engine overheating, with no other error messages.

Does anyone have any further advice?

Regards,

had

had wrote:

(...) why (...) the control system doesn't change without the air conditioning running, and the motor gets too hot

What do you consider to be "too hot"? What temperature does the engine reach when operating without the air conditioning system?
Please note that this is a closed, pressurized system. Temperatures above 100°C will not cause boiling! I don't necessarily consider it an error if the fans are not activated below a coolant temperature of 100°C.
Check out what happens at higher temperatures.

had wrote:

- Is it correct that the control system relies on a pressure sensor in the air conditioning refrigerant circuit, and not on the G62

?
Jain. The logic behind climate-controlled fans is roughly:
If the climate control is on, turn the fan on at a low setting (I don't know the exact percentage).
If the temperature is too high, the fan should run faster (I don't know the percentage or whether it should be dynamic or stepped).

Greetings.
Guste.

Hi,

"Too high" indicates a temperature of 100°C. This is the value at which I repeatedly encountered an error message on my V50, as mentioned above, but there is still no change in the control system. It's noticeable that the control system doesn't change at all, not even in the decimal range (without the air conditioning).

Regarding temperatures exceeding 100%, I still need to conduct further testing.

Regards,

had

Hi,

Here's some feedback:

In normal operation, the temperature is actually regulated starting at 100°C, while the air conditioning system begins regulating at an earlier point (around 87°C).
The fans appear to have three states, regardless of whether they are controlled via the air conditioning system or in normal operation.
- out, with a respective control value of 10.3%.
- on, level one, the control value is 16.6% or 19.3% (fan 2).
- on, level two, depending on the control value, which essentially takes on continuous values.

Regards,

had

Thank you for the feedback!

For posterity, it might be interesting to know at what temperatures each stage is activated. If you still remember, it would be great if you could record that information here.

Greetings.
Guste.

Hi,
In my car, the observed threshold values were within the normal operating range:
- Level I: approximately 99.9°C (both fans).
- The control value then stabilizes at approximately 101.7° (Level II, with both fans running).
- Above 101.7°, the control parameters are temperature-dependent.

The downshifting occurs at the same threshold values.
Regards,
had

had wrote:

- Level I, approximately 99.9°C (...) to approximately 101.7°C. - Above 101.7°, the control values are temperature-dependent.

Perfect, thank you!
Then we'll have something to refer to when the next person reports similar symptoms .