My 2004 S60 2.5 Turbo is making a buzzing sound when running the sound does not change on acceleration it stays the same. It seems to come from the drivers side. Any ideas?

 

Could be your Your vacuum pump is running all the time. The plastic switch that controls it is broken. You need to unplug the switch so your pump does not fry. Find and unplug this in the LF corner under the hood. It will be harder to stop the car when first started with no vacuum pump -

 

Thanks Hoonk I’ll be ordering a new vacuum pump

 

The vacuum pump runs because the plastic switch breaks. And yes you will be ordering a new vacuum pump once it seizes, but the switch will still be bad and make the new pump run all the time until it fries.