Odd pump/grumbling noise from engine bay when coming to a stop

[ainarssems]

On the D3 Aircon is permanently drive, not electric clutch like in older cars. It has variable valve which regulates cooling so it makes sense that it's still working for a little while after you press Econ button until the built up pressure dissipates

[rory_pamphilon]

Yeah interesting, that makes sense.

How big a job am i looking at to replace the AC pump?

[rory_pamphilon]

Originally Posted by mcs

This will likely be your air suspension compressor. It turns off when the car comes to a stop. It also pumps out a jet of air through the outlet to purge the air dryer.

As the compressor ages and it’s piston ring gets worn, it will become noisier.

Mike

So i just had the air suspension compressor replaced yesterday as it was taking a good while to raise the car in the morning.

Noise is still there lol! Driving my nuts.

[steamship]

Originally Posted by rory_pamphilon

air suspension compressor replaced yesterday... Noise is still there lol! Driving my nuts.

That's a real pain when you've gone to the hassle of replacing parts. Rereading the entire thread, did you ever pursue replacing the A/C compressor (not that I'm implying that that was the cause)? Just trying to eliminate possible options.

Is it possible to try and record the noise? I know it's not great, especially when the noise you want to record isn't that loud and the engine tends to drown most of it out. There's also the issue that unless it's a very unusual sound, most people won't pick up on it.

[ainarssems]

It's a bit of a long shot and hard to say without experiencing symptoms in person. Could it be climate control fan touching the casing?

I had kind of similar experience on Q7 after replacing climate control fan. Starting up, fan running at slow speed no noise; not sure if there was noise when driving and speed pushing more air through fan and making it spin faster and touch casing but me just not hearing because of other noises when driving. Or maybe it was braking forces shifting fan wheel just a bit so that it touches casing when braking but I could hear noise coming to standstill and it would stop after couple of seconds of being stationary. Taking it apart and reassembling making sure everything was seated correctly made it go away.