Help diagnose this problem
I have a Payne gas furnace. A few weeks ago, when I cam downstairs in the morning, I noticed it was very cold. The termostat said the furnace was on, but the furnace was not running. My serviceman came out, cleaned the furnace, turned the main switch off and then on, and it seemed to reset. It has been fine until yesterday when the same thing happened. Once I turned the main off and then on, it worked. Same problem happened this morning. He is coming back tomorrow. Any thoughts on the problem, as he could not find anything last time.