Whining (from aircon - not passenger!)

[jboult]

Hi,

I recently had my aircon re-gassed as it wasn;t doing anything. It seems to work fine now, and is certainly much colder than before. The only problem I've got is that every 30 seconds - 1 minute or so with the aircon on I get a slight whining noise from somewhere in the car. It's difficult to pin down where from, although it sounds like from behind the dash. It sounds like bearings (faintly) failing. If I switch the aircon off I don't get the noise.

I know it's not much to go on, but ideas anyone? Does the aircon compressor have lubricant problems that affect bearings if there has been no gas in for a short while? Any help appreciated!

Cheers/John

 

[Pete B]

Might it be the small fan located at the back of the AC/heating control unit in the dash. I'm told that they can clog up with dust & debris.
Very similar to the small fans in the PSU of any computer.
Might repond to a vacuum cleaner - but never tried that myself!
HTH

 

[robslade]

The compressor has a clutch and only kicks in when needed, typically a couple of times a minute. However it's in the engine bay... Mine was noisy for a while, but the noise was obviously from behind me. Turned out to be slack drive belt.

 

[jboult]

All,

Thanks for the responses - I'll investigate further this weekend and see if I can narrow down where it's coming from!

Cheers/John

 

[AndyC]

John,

I have (and have had for a considerable time) the same issue. This first occured when the car was still under warranty and the OPC changed the compressor thinking that was the problem.

A specialist told me later that this is a fluid dynamics issue and not a problem. Every 30 seconds or so the clutch on the compressor cuts out and as it does so the pressures change in the system. There is a venturi behind the dash and it is the change in pressure and flow through the venturi you can hear causing some kind of harmonic.

I believe (although don't know) that a small change in the pressure in the system (i.e amount of gas) can elliminate the problem but I've never bothered as it isn't doing any harm.

Hope this helps.

Andy

 

[jboult]

Andy,

Thanks, that could be it as it started only after recharging the system. Maybe all I need to do is wait for a while as it slowly leaks out...!

Cheers/John