I have a 98 SVT with 130,000 miles. Mostly freeway driven. The other day I turned on the AC while driving down the freeway, and it would not kick in. As soon as I got on the exit ramp, retudcing my speed, it kicked on blowing cold air. Does the AC need recharged? Im not to familiar with AC systems, so all help would be appreciated. I have had the blower resistor issue fixed! Thanks in advance