Hi Everyone. I am having a similiar issue on a 2007 Acadia. My compressor is cycling with permission withheld and permission granted erractically like the system was low on gas. I can command on in the ecm module and runs fine. Plenty of gas and good pressure. All sensors read normal. Pressure sensor, Ambient Sensor, Coolant Sensor etc. I can pull the A/C relay and still have the erratic permissions on and off. I can bypass the relay and compressor works fine also. Also when this started I also see the instrument guages making erratic movements. when i command the compressor relay on through the ecm it all stops. Question what would cause the erractic guages and a erratic signals to the compressor relay. Check the wiring harness completly in the engine bay. Ironically I had a 2007 acadia that everytime I turned right the whole instrument cluster went dead. that turned out to be a chaffing wire by the tail gate.