Hello my friends!

I notice a strange noise on departure when the car is hot!

Do you know what it could be?

Thank you!

On 26/09/2025 at 19:11, Cossty said:

Do you know what it could be?

Can you give any more info?

Does it happen every time,?

What about accelerate more or less?

What happens if you rev the engine in neutral etc?

Not all the time!

Only when the engine is hot and after long trips over an hour trips!

The noise is more intense in first gear, but I noticed also in second gear but lower! In R or neutral I didn't notice the noise!

I suppose is somewhat related to the electrical engine!

Hi Cossty,

I have exactly the same noise. Also when the engine is warm and I'm pretty sure it's my airco. I have the 1.0 TSI manual, so it's probably not the electronics. It's mostly in first gear, but also sometimes in second.

The first time I heard the noise was after a Airco Service. So I decided to drive a while with the airco switched off and I didn't hear the sound once. I contacted the garage and they did the service again and it was gone for a few days, but it came back. Less than before, but still there sometimes. And only when the outside temperature is warmer than 19 degrees. I don't hear the noise when the airco isn't working a lot.

I hope we can find out what it is exactly.

Edited 28 September, 202528 Sep by Lo_Hi

Yes you described perfectly! Same on mi car!

Thanks!

Tuesday I'm going to service and i let you know!

Ac belt slipping, or more likely the ac clutch slipping.

Maybe over gassed or change to High pressure switch....

Hi! Today I was at the service and they find a broken hose! That was the fault!

Thank you for help!

Hi Cossty. Thanks, for the update! Do you know which hose it was? And please let me know if the sound comes back.

@BlueWagon, yes it sounds like something is slipping when the airco has to work hard. I told the garage I thought it was over gassed, so they hooked it up to the filler a second time. Which was a temporary fix. The airco (compressor?) also makes a bit more noise since the airco service.

22 hours ago, BlueWagon said:

Ac belt slipping, or more likely the ac clutch slipping.

The AC compressor doesn't have a clutch, for many years VAG have fitted variable compressors that permanently run.

2 minutes ago, PetrolDave said:

The AC compressor doesn't have a clutch, for many years VAG have fitted variable compressors that permanently run.

and how those compressors turn on and off?

1 minute ago, imart143 said:

and how those compressors turn on and off?

As I said VARIABLE displacement, see from about 1:31

AC Compressors

Edited 1 October, 20251 Oct by PetrolDave

i googled it, thanks.

your video shows compressor with magnetic clutch..

Edited 1 October, 20251 Oct by imart143

11 minutes ago, imart143 said:

i googled it, thanks.

your video shows compressor with magnetic clutch..

Try again, I've changed the video to the correct one.

5 hours ago, PetrolDave said:

The AC compressor doesn't have a clutch, for many years

Fair doos

Belt idler bearing gone bad.....

On 30/09/2025 at 16:28, Lo_Hi said:

Hi Cossty. Thanks, for the update! Do you know which hose it was? And please let me know if the sound comes back.

@BlueWagon, yes it sounds like something is slipping when the airco has to work hard. I told the garage I thought it was over gassed, so they hooked it up to the filler a second time. Which was a temporary fix. The airco (compressor?) also makes a bit more noise since the airco service.

On 30/09/2025 at 16:28, Lo_Hi said:

Hi Cossty. Thanks, for the update! Do you know which hose it was? And please let me know if the sound comes back.

@BlueWagon, yes it sounds like something is slipping when the airco has to work hard. I told the garage I thought it was over gassed, so they hooked it up to the filler a second time. Which was a temporary fix. The airco (compressor?) also makes a bit more noise since the airco service.

This hose!

Thanks so much! That helps a lot. I will check the hose this weekend.