2002 Volvo V70 XC Q&A

2002 Volvo V70 XC Question: Whistleing brakes

I have a hissing sound and whistle from (a braking) component. Reason, when I step (press) on the brake pedal the noises stop. Any clue as to what this is. It sounds like an air leak. -
Answer 1
brake booster could be leaking -