I tried firing up my furnace today for the first time this year, and it will not ignite. When the furnace is turned on the blower motor starts, the igniter lights up, I can hear a relay click (assuming the gas valve relay) the funace does not ignite a flame, I do not smell gas, the gas valve is on, the main gas valve is on, I checked the pressure switch which seems to be working properly. After 3 cycles of this I get a single blinking light which indicates ignition failure (duh) says to check gas flow, gas pressure, gas valve, and flame sensor. Well the gas is on and my hot water heater which runs off the same gas feed is working just fine. The flame sensor is out of the equation as I am not even getting any starting flame for the flame sensor to pickup. I am guessing the gas valve is the problem but, it worked fine last year when I shut it down for the season so is it possibly clogged from dust? Any help would be appreciated.