I'm working on a York ISN that controls two York chillers. The both chillers are coming up with the error msg. no communication. It's almost like clock work about every 10min. The chillers shut down for 6 to 10 min. Then the whole cycle starts over. I can view the temps at the chillers from the ISN keypad. So I know there is some form of communication between the ISN and chillers. I do not have laptop or software. Any ideas.