Automatic recirculation HVAC fault - doesn't switch on poor air quality

[Corey_R]

Discontinuing the use of the ammonia based additive is a good thing anyway. Practically all good car glass cleaners advertise the fact that they are non-ammonia based - so I can't imagine it's good for the car (rubber and paint especially) if they advertise it as a selling feature.

[MkVIGTI]

I find myself changing the the recirculation myself as there is no indication for the sensor to be working, especially when it doesn't detect foul smell.

[leblaaanc]

I know this is going to resurrect this but I wanted to mention a simple testing procedure for anyone still playing around with this functionality of their car.

1. Plug in VCDS and goto Auto HVAC > Adv Measuring Blocks > Check Air Quality Sensor and Air Recirc
2. Ensure both read Fresh Air
3. Put some acetone (nail polish remover) on a paper towel
4. Drop the paper towel to the right of the air quality sensor
5. Listen for flapper to close (recirc should now be engaged)
6. Hurry back (or use logs) and you should see something like "Air Quality 1/2" and the recirc status should say something like recirc due to air quality

If you don't have VCDS you should be able to hear the flapper close. It takes only 1-2 seconds.

I did this procedure because I was unsure about whether the functionality was working due to my retrofit plenum having two motors that I had to chain together to get recirc to work and losing position sensors. It seems to work without the sensors (it might just not close as tight? but mine seems to just fine).

Anyway fun times. Also see towards the end of this thread if you were curious about the two motor plenum:
VWVortex.com - OEM MKVI Climatronic on a MKV on a RNS-510 Screen installed.

[Corey_R]

I know this is going to resurrect this but I wanted to mention a simple testing procedure for anyone still playing around with this functionality of their car.

Thanks, that's a very useful test! Cheers.