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Discussion Starter #1
I have a 2011 and would like to see if my AC blower is “blowing” at max. Can this be done via VCDS?


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How do you imagine "seeing" that your AC blower is blowing at max? I mean, what would positively indicate to you that it's blowing at max? Besides the climate fan indicator already showing you it's set to max, that is.
 

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The bitron controls the fan speed. Under VCDS, you can see the computed voltage and the actual voltage being sent to the fan motor. The more voltage, the more fan speed.

More info about the bitron than a sane person would want to know is here. Heater fan won't shut off

Note: later generations also have a bitron. It is just a circuit board attached to the fan motor. Early models have the bitron as a separate unit from the fan motor.
 

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How do you imagine "seeing" that your AC blower is blowing at max? I mean, what would positively indicate to you that it's blowing at max? Besides the climate fan indicator already showing you it's set to max, that is.
Good question and I’m glad you ask! I recently had AC services and I do get nice cold air, however when I put AC on “max” meaning temp at lowest setting “LO” and fan at full speed (full bars). At this point i wonder if fan is blowing at max speed because I’m my opinion it’s not blowing that hard. As a comparison when I set my 2013 GLI to max everything fan will blow much hard than in Touareg.


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Discussion Starter #5
The bitron controls the fan speed. Under VCDS, you can see the computed voltage and the actual voltage being sent to the fan motor. The more voltage, the more fan speed.

More info about the bitron than a sane person would want to know is here. Heater fan won't shut off

Note: later generations also have a bitron. It is just a circuit board attached to the fan motor. Early models have the bitron as a separate unit from the fan motor.
Could you possibly tell how/where to check this? Thank you


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Good question and I’m glad you ask! I recently had AC services and I do get nice cold air, however when I put AC on “max” meaning temp at lowest setting “LO” and fan at full speed (full bars). At this point i wonder if fan is blowing at max speed because I’m my opinion it’s not blowing that hard. As a comparison when I set my 2013 GLI to max everything fan will blow much hard than in Touareg.
This is not an answer on the question on how do you intend to check and decide whether it's running at max. VCDS will only see what the control modules see and "think". If you have the max setting displayed on the A/C controller, then VCDS will report the same thing.

Now, there might be possibly (albeit highly unlikely) some obstructions in your air chambers or even your blower motor could possibly run a lot slower than it should or did from factory (which, again, is unlikely without reporting an error), which could result the car not actually blowing at max - but I still can't see how you could determine whether this is the case or not, without having a reference base to compare to, like another Touareg from the same model year and trim level, or a new blower as a replacement.

Obviously a 2013 GLI (or any other car for that matter) is not a valid comparison reference by any means per se.
 

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VCDS will give a readout of the bitron computed voltage which is what the bitron should be sending to the fan. There is also has a volt meter built into the bitron so you can read the actual fan voltage being delivered via VCDS.

This is how the bitron error messages are set. The computer checks the computed fan voltage and the actual fan voltage. It sets an error codes if they do not match.

If the system shorts and the fan stays running when the fan should be off, you will see out computed voltage 0 volt and actual voltage 12.4 volts. IE: fan stuck on at max speed.

You can also have the opposite. Fan running below speed. Computed volts 12.4 and actual volts at 8.3 would let you know that the bitron is trying to run the fan at full speed, but due to an internal bitron malfunction, the full voltage is not going to the fan motor.
___

Now you can also have the issue that the fan motor brushes are worn out. In that case, there can be 12.4 volts at the motor, but now the error is in the motor itself and not in the bitron as above. In this case you would see computed voltage 12.4, output voltage 12.4 and the fan would be spinning slow or perhaps not spinning at all.
___

If you want to test it old school...

The fan in the T1 and T2 only has only two electrical spades. One is the voltage and the other one is ground. Connect a volt meter read the voltages as you move the fan speed button up and down. You should be able to "see" the fan speed change. The voltage will go lower (at slow) and higher (at fast) as you change the fan speed. True off should be zero volts and full speed should be whatever the full voltage +12V line is at. I have used 12.4 volts above in the examples.

As for testing the fan at full speed, you supply the full battery 12.4 volts to it. It either spins up to your satisfaction or it does not. Now, technically you could find out the full speed RPMs of the actual motor is. You then buy a special tool (optical tachometer) to read the actual RPMs of your motor. In the real world, everybody just tests fan motors by putting 12 volts on them and seeing if they move enough air.
 

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Discussion Starter #8
Thank you very much for all the great information.


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Discussion Starter #9
Do the 2011s have an AC blower resistor? Any chance this might be the culprit?


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Do the 2011s have an AC blower resistor? Any chance this might be the culprit?


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Touaregs do not have a blower resistor. Instead they use the bitron to control the fan speed.
 

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Discussion Starter #11
Touaregs do not have a blower resistor. Instead they use the bitron to control the fan speed.
Thank you. I was asking since I’ve been told that a bad resistors cause solo at issues that I’m having. That said. Is bitron a physical part that can also go bad and cause similar issues as a bad resistor?


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Discussion Starter #12
VCDS will give a readout of the bitron computed voltage which is what the bitron should be sending to the fan. There is also has a volt meter built into the bitron so you can read the actual fan voltage being delivered via VCDS.

This is how the bitron error messages are set. The computer checks the computed fan voltage and the actual fan voltage. It sets an error codes if they do not match.

If the system shorts and the fan stays running when the fan should be off, you will see out computed voltage 0 volt and actual voltage 12.4 volts. IE: fan stuck on at max speed.

You can also have the opposite. Fan running below speed. Computed volts 12.4 and actual volts at 8.3 would let you know that the bitron is trying to run the fan at full speed, but due to an internal bitron malfunction, the full voltage is not going to the fan motor.
___

Now you can also have the issue that the fan motor brushes are worn out. In that case, there can be 12.4 volts at the motor, but now the error is in the motor itself and not in the bitron as above. In this case you would see computed voltage 12.4, output voltage 12.4 and the fan would be spinning slow or perhaps not spinning at all.
___

If you want to test it old school...

The fan in the T1 and T2 only has only two electrical spades. One is the voltage and the other one is ground. Connect a volt meter read the voltages as you move the fan speed button up and down. You should be able to "see" the fan speed change. The voltage will go lower (at slow) and higher (at fast) as you change the fan speed. True off should be zero volts and full speed should be whatever the full voltage +12V line is at. I have used 12.4 volts above in the examples.

As for testing the fan at full speed, you supply the full battery 12.4 volts to it. It either spins up to your satisfaction or it does not. Now, technically you could find out the full speed RPMs of the actual motor is. You then buy a special tool (optical tachometer) to read the actual RPMs of your motor. In the real world, everybody just tests fan motors by putting 12 volts on them and seeing if they move enough air.
Could you guide me to where within VCDS I can find this info? Thanks


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