Advice needed - Jet powered coolant fan!

[Varrick]

Thanks fella's, assume this may point in the direction of the thermal switch / coolant sensor?

[ainarssems]

Considering you have fault code 18308 - Coolant Fan Control 2 P1900 - 004 - Open or short to ground I would be more inclined to believe it's the fan control units fault, they do fail occasionally, unfortunately they come together with fan and dealer does not sell them on their own. Check the temperature readings in VCDS if they all seem OK it will probably be the fan control unit. You might also be able to check fan duty cycle in measuring blocks in VCDS.

[Varrick]

ainarssems - thanks, will take.your advice and check this out again! Thanks again to everyone concerned for your help, great forum.

[ainarssems]

Check out this Link: http://www.audi-portal.com/en/diagnostic/ecu_12813.html

The bits that you are interested are measuring blocks about temperatures and fan activation, duty cycle as below:

Measured value block 132: Cooling
1)-
2)-
3)-
4)Status of cooling
(Meaning of 8-digit number block)
1 2 3 4 5 6 7 8
X No fault in system
X Thermostat actuator active
X Fan actuator active
X Control deviation (0 > specified temp; 1 < specified temp)
X Fan speed 2 active
X Fan speed 1 active
X Vacant
X Hot countries function encoded
(1=Condition met; 0=Condition not met)

Measured value block 133: Automatic fan detection
1)-
2)-
3)-
4)Status of cooling
(Meaning of 8-digit number block)
1 2 3 4 5 6 7 8
X Fan configuration plausible
X 0=Single fan; 1=Dual fan
X Fan configuration detected
X Vacant
X Vacant
X Vacant
X Vacant
X Vacant
(1=Condition met; 0=Condition not met)

Measured value block 134: Temperatures
1) Oil temperature [°C]
-60 - 195
Substitute value in case of defect: 195
2)Ambient temperature [°C]
-50 - 77
Substitute value in case of defect: 77,5
3) Intake air temperature [°C]
Ambient temperature - 110: Engine warmed up at standstill
Substitute value in case of defect: 20
4)Engine temperature combi [°C]
80 - 110: Engine warmed up

Measured value block 135: Fan actuator
1)-
2)Duty cycle fan actuator 1 [%]
0 - 100
3)Duty cycle fan actuator 2 [%]
0 - 100

Measured value block 136: Fan actuator
1)-
2)-
3)-
4)Fan run-on [Text: Off / Run-on]

Measured value block 137: Air conditioner requests
1)Air conditioner readiness [Text: AC-Low/AC-High]
2)AC compressor [Text: Compr. ON / Compr. OFF]
3)Pressure from air conditioner [bar]
0 - 40
4)Fan request from air conditioner [%]
0 - 100

Measured value block 138:
Thermostat diagnosis (no basic setting possible)
1)Engine start temperature [°C]
5 - 30
2)Mean engine air mass [g/s]
11 - 72
3)Mean vehicle speed [km/h]
35 - 120
4)Result [text: Test ON / Test OFF / Syst. OK / Syst. n.OK / Abort]
Syst. OK

Measured value block 139:
Thermostat diagnosis (no basic setting possible)
1)Engine temperature in diagnosis [°C]
> 76°C (specification for successful diagnosis)
2)Actual air mass integral [kg]
0 - 46
3)Specified air mass integral [kg]
10 - 14.2 (specification for successful diagnosis)
4)Result [text: Test ON / Test OFF / Syst. OK / Syst. n.OK / Abort]
Syst. OK

[Varrick]

Thanks again ainarssems, I'll pass this on. Hopefully will get to the bottom of it soon!

[HPsauce]

Definitely worth a call to our sponsors to see what they have and whether they can split the controller from the fan.

[mattylondon]

Welcome Varrick