My service manager always says to put a time clock on for air defrost when we start having ice up problems.It seems to be a great fix and less midnight calls. I know people in and out and warm/hot product will cause ice up, but what else will cause it out of nowhere. Charge good, s/h good all ideal conditions from a troubleshooting standpoint. (A couple locations I am thinking of.) Human Factor? The clocks work but I don't want to be a lazy hack if I am overlooking somethig. Any thoughts?