Do i have the "whistle" problem?

[sam48is]

It's not really a whistle, it's more like the sound of a puncture (like when letting air out of a tire, pssssss). I can't tell where it's coming from, somewhere from the engine or behind the dash. It's not audible at low speeds, but becomes very noticeable at 70+ mph. It happens either when I let go of the gas pedal or when I accelerate, but goes away when I'm maintaining the same speed. It also completely goes away when I turn off climate control.

Any ideas?