HVAC Intermittent No Power
 

Twice now, I have had an intermittent issue, where my HVAC has had no power. I have a 2005 F250 6.0 PSD, with the auto HVAC. There was no fuse blown. I shut the truck off, and then restarted it, and it was working. Display was blank, and the buttons were non responsive. What could cause the temp loss of power?