I called after hours when our furnace wasn't working. The on call guy (Jeff) answered right away. Quoted me $135ish for an after hours service call which seemed fair to low to me but he insisted on walking me through the problem since I told him I'm not that knowledgeable but not completely out-to-lunch either. He was familiar with my Luxaire (York apparently) furnace and after about 10 min we concluded it was my Nest thermostat that was the problem. Saved me $135 (plus tax) and my little ones never noticed the drop in temp at all - thanks Jeff!