noisy air con compressor?

[dtwoi]

ive got a 2005 2.0 tdi a4 avant with a noise coming from the air con compressor(i think??) its like a metallic knocking noise that is much worse when the air con is switched off(econ mode) there is still a bit of noise when air con is switched on but its only very slight and probably acceptable for a car with nearly 100k,so has any one got any ideas to what my problem might be? ive had a few differing opinions one thinks change compressor another thinks its poss the clutch/pulley thats noisy and someone else has suggested maybe a re gas and oil so any help or experiance was be greatly appreciated as holding out hope that its not the £600 compressor!

[Alan02]

Without dropping the belt off to check pulleys etc,your only guessing but a faulty clutch on the compressor is possible.It could be that the spring-plate hub may not be clearing the pulley when disengaged or it is damaged in some way.But i guess you need to look at it in more detail.

[dtwoi]

Thanks for the reply alan do you know if the clutch mechanism is separate/removable on the compressor i reached down and felt inside the compressor pulley and found theres something in the middle of the pulley that when moved backwards and forward by hand it sounds like the noise im getting but obviously on a much quieter scale then when spinning at engine speed, so is there something that cushions inside the pulley or should there be a little bit of play in what ever it is in the middle of the pulley? sorry for the really vague discription but i know little or nothing about how the system works
thanks for your help

[Audi_man]

Hi

I had the exact problem that you described, when the air con is OFF the noise is worse, and when it is ON the noise is less but still there. I changed the compressor and this fixed the problem, and yep it cost about £720 fully fitted.

[dtwoi]

yeah i realise if i change the compressor it will definatley fix the fault but thats the last resort due to the cost so if its possible to repair (ie a new pulley@£99) rather than a new compresspor unit +fitting+evacuate and re-gas allthough sods law says a fit a pulley then end up shelling out or a new compressor as well!

[dtwoi]

ok so ive established its the pulley on the compressor thats noisey namely the actual centre of the pulley,now ive rang the dealers and they tell me the pulley is available separately and seriously cheaper than a compressor.
so got under the car and had a look tonight and all i can see is a 7mm nut on the front than will turn only spo far in each dirrection but dosn't actually come off,so wondered if anyone knows how the pulley comes off as im hoping to remove it without removing the pump and adding more cost to the repair with re gas ands oil etc

any help greatly appreciated (any techies)