HVAC system noise after shutoff?

[diagnosis]

I doubt this is normal.

There is an odd sound coming from under the passenger side dash, if I had to describe what it sounds like.... humming, possibly the sound that a servo would make?

My guess is the HVAC control constantly adjusting itself. This normally wouldn't worry me, although it continues on after I've shut the car off, and removed the key.

Would my assumption be correct, or is there another common problem that may be the cause of the sounds I am hearing?

Any insight, input or ideas on this would be greatly appreciated.



Graham.

[akira112]

Same problem here,
But from other threads it sounds like this might be the norm.

[A4.Rob]

mine does that, i think everyones does.

[b6onboost]

Its normal and only happens if you had the HVAC on when turning off the car. It sounds like a spaceship powering down.

[SleeperAvant]

It's a cool noise really.

[boostedAvant]

My blend air doors make a noise too, besides the air plane power down noise that I think is fucking awesome.

[diagnosis]

Does the airplane/spaceship sound stop after a while? I guess that is a reasonable description of the sound, but it continually starts and stops, and the humming sounds carry on for 2 - 6 second intervals. Even after the car has been sitting untouched for up to 5 hours, the sounds continue....

[1stb6]

HAHA funny i see this thread now...pulled up to the store with my GF in the car and it was real quiet...i turned the car off and she was like "wtf was that"..i continued to explain it was the flux capacitor cooling down

[diagnosis]

Well, I guess it's a bit of a relief that it seems to be a somewhat common 'problem'... thanks for the input.

[diagnosticator]

The turbine spin down noise after shut down is the condenser fan spinning down, not the HVAC system inside the cabin. The other common noise from the inside HVAC gear is the servo motors trying to set the flaps to the positions programmed, but due to bad feedback pots on the servos, they hunt around instead. Resetting the channel 001 adaptation using Basic Settngs can help, but it's typically only temporary. Audi has updated servos for this problem.

[SpacemanSpiff]

Take your glovebox out and you'll see the blower motor assembly back there. When the car is turned off, you'll be able to watch the flap on top move from it's "Fresh Air" position to the "Recycle" position for the next time it starts. It does this so you don't suck exhaust fumes back into the car when you start it up in the morning. In fact, if you listen the next time you start driving down the road, you'll hear a similar noise when it moves back to "Fresh Air" position. I'm not sure if it's a timed or distance related trigger (probably just time), but it happens every time without fail on my car.

I had my box off for almost a month during my stereo install and watched it every day. Normal operation.

[dpatel]

This air flap motor is known to go bad. Check for codes. Also sometimes you can hear it when you come to a stop as it switches to recycle air instead of fresh.

[diagnosis]

The turbine spin down noise after shut down is the condenser fan spinning down, not the HVAC system inside the cabin. The other common noise from the inside HVAC gear is the servo motors trying to set the flaps to the positions programmed, but due to bad feedback pots on the servos, they hunt around instead. Resetting the channel 001 adaptation using Basic Settngs can help, but it's typically only temporary. Audi has updated servos for this problem.

I think that may be the problem! I am relatively new to the Audi scene, but I am assuming that I will need a VAGcom to access and reset the basic settings? Also, if this is the problem, are the updated servos under recall?

[TwinTipSkier]

Mine used to make a horrible moaning noise when they would shut when I first bought my car, LIGHT dab of wd40 on the pivot points cured the moan.
After ignition off and pulling the key, I can still hear an intermittent noise as well.
Pulled the glove box and drove around like that for a week to investigate. Just as diagnosticator said, they were hunting around.
Glad to hear I'm not alone.

hah, we all drive around without gloveboxes

[diagnosticator]

I think that may be the problem! I am relatively new to the Audi scene, but I am assuming that I will need a VAGcom to access and reset the basic settings? Also, if this is the problem, are the updated servos under recall?

Yes, VAG-COM is required to readapt the servo motors. The revised parts are not associated with any recall.