Dispatched to do furnace clean and tune. Cycled system. Furnace did not fire. Used jumper on main board terminal strip. Was able to jump cooling, and fan, was unable to jump heating. Tested voltage on all terminal lugs. Had correct voltage, main board has failed inspection. Furnace will not fire. Found igniter worn and cracking. Heat exchanger is very worn, rusted and corroded. Average life expectancy for this unit is 14 years. This system is 17+ years old and worn. Unable to do cleaning unit repair is done. Recommend repairs of replacement. Quote for full replacement of furnace is $2600.00. Office to follow up on Monday. No cleaning cost collected at this time.