hi, i'm admittedly a newb and my car care ability is not novice but not much more than being able to put in a stereo and subwoofer and change the oil, filters, and bulbs in my car. i have a '98 S70 volvo sedan with about 160K miles. my A/C unit doesn't blow very cold air particularly when it gets very warm (85+) outside. is this normal? due to age of vehicle and system? my question is how to improve the ability for it to cool the car? thanks in advance.