Air Con Hum, what is it?

[Rob.]

My Fabia's air con's started... buzzing.

It buzzes at an equivalent pitch to the engines revs, so the higher revs the higher the pitch it buzzes / whines / droans at.

My last Fabia also did this and my then Mech couldn't find anything wrong.. but this noise defiantly isn't meant to be there, The Air con still works as well as it ever did.

The fact it's linked to the engines Rev's point to something around how it connects to the auxiliary drive belt? Does the Aircon have a bearing that can fail.. would low gas cause running issues as well as poor performance? Does it have some kind of clutch because when you turn off the air con the noise stops straight away.. turn it back on and there it is again whirring away. could it be a complete compressor failure :(

Anyone any suggestions? Car goes in for service next month at Browns so would like to give them a heads up to sort it.

Thanks

Rob.

Edited 6 October, 2010 by Rob.

[Rob.]

Bump... I can't be the only one... Any ideas?

[joenitro]

Hi Rob

Did you ever find a solution to your problem? My 2004 vRS has been doing this for three years now! Although two re-gasses temporarily solve the problem!

[Chris Coates]

An air-con pipe vibrating on something, transferring vibration inside?

[tag1_uk]

My car had the exact same symptons. I had it service and an air con service whilst they were at it. They topped up the gas but didn't report any issues. Noise is still there :-(. It certainly didn't make that kind of noise 6 months ago and as you report it gets cold ok so I've no idea what is wrong until it goes bang.

[MoggyTech]

Does the hum stop if you press the recirculate button?

[Beancounter1980]

Do you all have a custom radio installed? I have noticed the plastic between the top of the aircon and radio slot can buzz. In my case I needed to push and pull it to get it to stop.

Cheap plastics etc

[Rob.]

Well, I got it serviced and it turned out the compressor was completely out of gas...

It went away for a while but started to come back this summer...

I did more reading on here and I think it's the compressor bearing getting past it's prime. As for it only doing it when it's been in use for a little while, even though the compressors always engaged, I suspect it only gets ropey as the compressor warms up and passes the heat through to the bearing when working hard, as oppose to just sitting in the chain not trying to do much...

If it goes pop, I'll report back. Thing is.. I'm sure I'm starting to hear it quietly every so often even when the ac's been off.. which goes along with the bearing theory,... which is bad!