I am not so sure there is a tech support network for york. At least not in canada, as I have never been given a number to call and when I did a number to call the response was to fill out a form and that was not replied too either.
The same problem occurred again this morning. So to try and narrow it down a little further I had the customer set the aux heat lockout temp to 25 from 35. We have been below 35 the last 2 mornings and coming out of nighttime setback the aux heat may not be deenergizing once set point is met which sort of points to that as I have previously posted yesterday what I found when I arrived on site