VEHICLE STOPPED WITH FOOT ON BRAKE. A/C COMPRESSOR KICKS ON AND VEHICLE'S IDLE STARTS TO RACE SO FAST THAT THE BRAKE DOES NOT HOLD THE VEHICLE WHICH CAUSES THE VEHICLE TO REAR-END THE VEHICLE IN FRONT. IDLE KEPT RACING UNTIL VEHICLE WAS SHUT OFF. WHEN RESTARTED THE IDLE WAS BACK DOWN. *JB