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I have a noise from the ac that follows the rpm. It appears when the engin is warm and with the ac on. Don't have it with the ac off! Any ideas what the problem could be?
VW Polo 1,4. 2014

Please specify 'from the ac' as the ac system is widely spread from the AC compressor in the engine bay to the air outlets in the dashboard. Makes it a bit easier to help. Thanks!

Might be a faulty compressor or compressor clutch. Replacement is the only solution. Happens a lot unfortunately.

It`s a bit difficult to specify exactly where it comes from, all I can say is that I hear it when I sit in the car and not when I`m outside the car and it follows the rpm. Stops when I turn of the ac.

Sounds like you have no gas in system. Best get it checked for leaks.

Will do that next week

I think that there were quite a few people have had problems with Sanden compressor failure due, it has been said, to debris being left inside these compressors during initial compressor build, sounds crazy but seems to be true in some cases! If that is your problem, I'd think that with the AC off there will still be a noise but maybe not so loud as these compressors are driven directly from the auxiliary belt and so have no clutch, just variable displacement to match the delivery of refrigerant with demand.

Problem solved. The system needed a refill.

Hi everyone, I found you on this forum through Google and have just registered.
My Polo (2014 reg 1.4 petrol, which I bought brand new in 2014) has a similar ac noise issue like Sankan's. It makes a loud whining noise when the cooling is turned on for a while. The noise does not come up immediately, and it simply stops when the cooling is stopped. As the a/c was just serviced by the dealer about 1 year ago and it does cool down well, it does not seem to have run out of gas. I spoke with the dealer when the car was serviced a couple of months ago. I was told I needed a new compressor. I can't believe it! For a car of less than 30k miles on the clock, the compressor simply failed when it is still cooling. Do any of you have similar experience ? I appreciate your pointing me to the right direction. Thanks very much in advance.

Paying to replace a compressor at that age of car would annoy me a lot as well, I've never ever had to get that done and I've owned VW's that were 13 years old when sold on!

But, as I posted a lot earlier, it does seem that some of these Sanden compressors are complete rubbish. ECP sell a Sanden replacement but for some reason it is a slightly lower capacity unit, maybe not an issue in UK weather/temperatures though!

Edit:- my other suggestion would be to take that car to a proper AC repair place, as they will understand these chillers a lot better than a VW Group dealership who will just replace parts until it is sorted. People at a proper AC repair place will connect a manifold gauge set to it and monitor its pressures while running etc - then make their mind up as to what is wrong.

Thanks RUM4MO for the advice. I will see if I can find a local ac specialist. In addition, I have no idea if the compressor is of Sanden or not. It is the original VW one came with the POLO (2014 reg). Nevertheless, my gut feeling does't trust this dealer.