Over the past summer we had some issues with the thermostat in that you would have to turn it on and off several times to get it to work. Last week we had our heat on for the first time and had to do the same thing. Shut unit off as temperatures went back up and needed neither the heat or the ac. Last night unable to get furnace to start at all. Could it be the thermostat itself? There is no click or other reaction when the thermostat is pushed up past the current temperature.

Take t-stat off wall, hook red wire and white wire togeather and see if the furnace works