Touareg :: Air Recirculation Valve Randomly Go Into Oscillations For A Couple Of Seconds

I'm experiencing an annoying problem with the air recirculation value on my Touareg. Basically it will randomly go into oscillations for a coupld of seconds, where is sounds like the vent blowers are either speeding up and slowing down quickly, or the recirculation valve is opening and closing rapidly.

This seems to happen randomly, and usually only lasts for a couple of seconds. I've taken it to the dealer twice but they aren't able to determine the cause of the problem.

Here is my theory for what it's worth. I think it may be the recirculation valve, whose job is to close the external air value from outside air to recirculating internal air when it senses pollutants in the outside air. I think the problem is caused by one of two scenerios;

1) the sensor is bad or failing and sends random signals to the vent controller causing it to open and close rapidly, or
2) The control circuit is not tuned correctly, thus instead of waiting to see if the pollutants it senses is sustained, it reacts instantaneously.

The noise this produces is quite annoying!