That is typical for the johnson control when it is bad. Lennox bailed johnson controls and now uses a honeywell. The Lennox part nimber is 53L90. It also comes with wiring instructions and a new sensor. A Lennox tech will have the part on his truck. I keep 4 of them on board at all times. I would recomend a pro put it on and give the furnace a good check. I have been finding a few G-26 heat exchangers cracked.