I got a 2004 tahoe, that my step dad drives to work and, he said when he was sitting in it talking to a friend, a loud air leaking noise was heard, when turning the car off there is a loudise noise of air discharging, but the are still blows cold air should i be worried, oh and the air discharging sound like it coming from around tye front of the car, I wasn't able to find it,