A3 aircon noisy.

[catso]

2004 A3, 3.2 - just noticed that when I switch on the A/C there is a noise, kind of like a grating/whining fan (changes pitch with fan speed). It doesn't do it if in 'economy' and just blowing air, only when the A/C is on.

Also (maybe related?) a few days ago the aircon was cutting out, infact the whole fan/control system stopped responding whilst stuck in traffic but as soon as I was moving again it was back to working OK - did this a couple of times on that day but has been OK since, other than the noise.

Any ideas?

[va1o]

Compressors on these are prone to failure. Has it had anything replaced in the past?

[catso]

Some years back the ventilation packed up so that, although the fan was running no air would come out any of the vents. It had some flap or valve replaced under warranty but otherwise has been fine.

I was wondering if it might be the compressor rather than the fan because with A/C off but with the (same?) fan running it doesn't make the noise. It is still working but I wonder for how long, is there an easy way to diagnose?

[page3]

My 2008 A3 had the same noise when the Aircon was on. Noise increased with speed of fan, and disappeared when on low. Almost sounded like the fan blades were rubbing against something.

Via a bit of goggling I found that the fan assembly is accessible from behind the glovebox and the fan motor can be prone to making this noise. Reports are that it could be indicating imminent failure, but others said it could go on for years.

After the last service and pollen filter change (under the glovebox I believe) the noise has almost gone away. The fan now needs to be on max for me to hear anything.

Never did track down if it was related to the aircon or simply that the air is being routed differently when the aircon is on.