Comfortmaker GNK125N20A3 not getiing gas, how to test valve

[JJ 109]

My furnace (Comfortmaker GNK125N20A3) will not get hot. The blower runs but the burner will not ignite. I do not believe the gas valve is opening, I cannot hear it click open.

Furthermore, when I remove the plug in gas line after the valve, there is no gas present.

Before I replace the valve I would like to check it somehow to ensure thats the cause of the issue, not something else that is wrong and not allowing it to open.

Thoughts?

[JJ 109]

BTW the valve is a Honeywell SV9501

[JJ 109]

Update

I was checking the pressure switch so I jumpered the 24v supply (black) to the pressure switch feed (blue).

This cause the furnace to light. So though I had it. Then I checked resistance of the pressure switch. OC when the blower was on, CC with blower off. Hmmm, seems appropriate. Then I found a another thermal switch in series on the blower and it is also CC. So both are OK it would seem.

From there the wire goes to the board.

Not sure where to go form here yet. Does this mean the board is bad? Its a Honeywell ST9120c-4057.

[Bobice]

See checkout procedures : http://customer.honeywell.com/techlit/pdf/PackedLit/69-0781.pdf