After I removed my smog pump, I re-routed my serpentine belt with the instructions I found in the tech article section. Now when I turn on my AC, I get a vibration from the belt. I then purchased the 10129569 smog pump delete pulley from GM parts direct and put on the 968K6 belt, but I still have the vibration. The vibration occurs when the RPMs drop after acceleration, anytime I lift my foot off the gas pedal.