I had a new furnace installed 3 years ago. (no air conditioning)Recently when I turn the thermostat up, the furnace ignites,and a minute later the blower blows cool air for about two minutes then stops and the cycle immediately starts over again until about the fifth time when the air is warm and it stays on for about 9 minutes.then the next cycle for about 10 minutes . Then it stays on until the desired temperature is reached. I do keep the house very cool while I am gone, but this has never been an issue the past two years

You have a shutoff thermostat on the furnace it should be high up in with your burner I had a wire burn off in that on mine so I'm thinking it might be the same problem but not sure