I have a 13 yr old Comfortmaker RPJ II gas furnace controlled by a Honeywell digital thermostat. I have it programmed to turn on at 5:30AM. Lately, the furnace is not turning on (igniting, firing, blowing) in the morning even though its cold enough and the thermostat is sending a signal to the furnace to turn on. When I cycle power on the furnace by unplugging and plugging the main power cord, it immediately fires up and works properly for the rest of the day and evening. However, the next morning the problem starts all over and I need to cycle power again to get it to work. The furnace is in the attic. Any suggestions? Could their be a bad temp sensor that is disabling the system and gets reset when I cycle power? Thanks for your help.

If it has a flame sensor clean it.