I have the above furnace, 2 yrs old. Approximately, every two days, sometimes more, the thermostat will signal the furnace to start, the beginning sequence starts but there is no "click" I here when functioning normally right before the ignitor starts glowing, and the unit will shut off. A green light, normally on, visible through the side of the controller (I assume?) will then start blinking. Ive had the service people here 3 times but each time they come, it IS working and they wont do anything. What part is not working? The controller ?, the ignitor?, some sensory unit isnt getting a signal? At a loss and really appreciate any help.