Since my last response, I did find out that Freightliner currently has two recalls out for my Coach (and some of your's as well I'm sure) that could be the root cause of intermittent dash AC operation. There is a recall on the PDM, or Power Distribution Module. This device sends power to several components including the AC clutch. After heating up, the board starts shutting down components, thus the intermittent operation. I suggest you call Freightliner and inquire about these recalls by giving them your VIN. It could save a fortune in diagnostic charges by a repair shop.