My radiator fan went out and I was only able to run the A/C while moving at highway speed. Along the way, I removed the cabin filter to get a new one. ALl of a sudden (coincidence?) the climate control system would default to "Econ" but would allow me to run A/C in "Recirculate".

I fixed the fan and put the cabin filter in, but I still cannot run on AUTO with fresh air A/C. I can only run A/C in recirculate....

Any ideas?

Thanks!

 

The car has a pollution sensor that may be indicating to the HVAC system that the air is polluted and it is holding the system in recirc. Might find the sensor and test it to see if its working right.
By the way, you give no idea of which model you have, all the A6's may not have the sensor.

 

Thanks... I'll look into that.

Its a 2000 A6 Avant Quattro 2.8

 

I lloked in my Bentley book for the Air Quality Sensor location. It says it is in the housing of the cabin filter. I don't see it. I assume it would be outside of the baffles?

Where is the Air Quality Sensor located specifically on a 2000 A6?

 

I would describe the air quality sensor as being more on the front of the housing for the cabin filter. There is a little bracket there that the sensor slides on to. It is pretty fragile and would be easy to damage the bracket. The sensor is at the end of a long wire that comes across the front of the car by the battery.

 

OK... so after a week or two of Recirculate only, the Climate Control got its act together and the fresh air A/C is back to working correctly.

With unresolved cam seal and exhaust manifold leaks, I really didn't need to spend more time troubleshooting the A/C... back to the other stuff.

Shade Tree Audi Tech at
ScottRodsCustoms