My CEL light came on today when the A/C was on. with the A/C on, the car had an odd vibration coming from the engine bay whenever i was idling at a light (in gear, in neutral, didn't matter). A/C works though, if the A/C works, is there any reason to do this fix? I"m just trying to diagnose the issue. Gonna either stop at dealer or autozone tomorrow to have codes read.