My partner went on a service call for this unit because the heat wouldn't come on. It has 2 boards on it and the board with the indicator light is blinking 3 times. On the unit, it says that if the light is blinking 3 times is is usually flame overthrow but he checked it and it checked out ok. He has ordered a new board but we are hoping someone has info or troubleshooting advice on this unit. We're not too familiar with Lennox units.