Atwood Furnace Problem. Help?

1. Turn the furnace on, then go outside to the outside vent. Wait until you hear the Ignitor click. When it does, IF the gas valve is opening, but does NOT ignite, you will smell the LP. If you do NOT smell the LP, then the gas valve is not opening. A quick test for the gas valve is this, you access the LP line where it is connected to the Gas valve on the furnace, you attempt the Light sequence, when the Ignitor clicks, you whack the gas valve lightly with a hammer. IF the furnace lights, you have a defective gas valve. If it does not light, then you may still have a defective gas valve, but you need to do more testing. Gas valves can fail when the temp gets to freezing and the valve body contracts from the cold slightly to keep the plunger from pulling down. Your year model as you found out does NOT shut down after a no light, but continues blowing cold air. Doug