Hello all, Needing a bit of help here. I've got a Ducane furnace that was installed in 2007. Lately is has started having an intermittent startup failure. When I call for heat, there is a what sounds like a relay click from somewhere inside, and NOTHING else. The heartbeat light on the control board changes from steady heartbeat to a 3 flash error. Which is a pressure switch error. It may fail like this 10-15 times, and then all of a sudden work fine the next 1, 2 or 3 cycles, and then fail again. When it does work, it works flawlessly. I have called in a technician and without any testing at all, told me the control board is failing and wants $500 to replace it. His reasoning is that with nothing happening such as the inducer fan or anything starting that the board is at fault. He spent 5 minutes of browsing at the furnace to come up with this conclusion. I'd like the input fro mall you fine folks on this to see if you all agree with his diagnosis before I let him go ahead. Any help would be appreciated.