I've a 22 plate Octavia 1.0 tsi, and its always been a little noisy; it makes sort of a revving noise from behind the passenger side of the dash. Especially noticeable in 1st gear when the revs are higher.

Having always had naturally aspirated cars, I'd assumed the noise was the turbo waste gate or something, however today I noticed it goes away if I turn the aircon off!

The best i can describe the noise is a sort of low warbling, that echos the engines revs. After a long journey it also appears to be there in the background; the noise sort of surges on and off.

Has anyone else experienced anything like this? I've read elsewhere this can be due to the Aircon needing regassing. My aircon is nice and cold, so I'd always assumed it was ok.

Having come to a Skoda from a 25 year old vw bora, which was never regassed, always cool and silent - I find it odd that I might need to regass a 4 year old cars air con. I was always of the mind not to touch it if it works after horror stories of people having a regass and the seals not holding up.

Should I get it regassed? Is there any risk doing so?

The refrigerant gas in your Bora will have been one of the now banned refrigerants. Modern cars are running refrigerant gases which are kinder to the ozone layer - but they do seem to leak a little more and are certainly more expensive.

Take your car to a proper A/C specialist rather than the dealer. He will empty your system, refill to the correct level - often with a marker dye to trace if you do have a leak. The seals will be fine and should benefit from the correct amount of gas / lubricant in the system. Max pressure is regulated in the A/C circuit and will not be increased with the correct amount in. The anecdotal statement that regas leads to blown seals omits the question of why were they regassing anyway? Seems to indicate the fault was present before the regas.

My wife's 2016 Rapid, with the 1.0 litre engine, always had a quiet chirrup from the A/C from new.

Thanks. I'm guessing by "quiet chirrup", you are implying your wifes car made a similar noise.

I was simply thinking about booking it in at one of the national chain garages that advertise regassing, but maybe I'll look for a local specialist.

I guess I just want to avoid doing anything if the noise is considered normal; I've not come across noisy aircon in a car before. Seems odd.