Hi to everyone. I am new to this forum. I need your help. I have 2007 S60 2.5T with 33,000 miles. When I turn on my car, and the conditioner is on, the car makes almost a hissing sound, like sort of a patient on ICU machine. It seems as sound comes from the dash board. The air is cold. Then, every 40 to 45 sec the sound repeats. If I turn the conditioner off, the sound stops....It feels like the car is breathing on its own every 45 sec....what is it?

 

your car still under warranty, take it in to the dealer