RV Repair: Furnace Wont Light, suburban furnace, board tester

Question
Hello Darren,

My Suburban furnace SF-25F will not light. I have checked the 12v power and the gas supply which are fine. I removed the unit and disconnected the gas supply but left it wired up. The blower works fine and I observed the gas valve open. I replaced the electrode. My question is, when I run the furnace through a cycle, shouldn't I be able to see the electrode spark? It doesn't so I'm guessing that the board is bad.

Thanks for any input you can give me.

Answer
Norman,
      Yes, you should be able to see the spark at the electrode provided that the wire to it or the electrode itself aren't shorted to ground.  You can pull the wire loose from the board and hold it about an 1/8" from where it connects and if something is shorted to ground it should spark across the gap during the ignition cycle.  You will want to use something with insulated grips to hold the wire.  If it doesn't spark then, then the board is probably defective.  Most RV repair shops will have a fenwal board tester that they can check the board with.  I hope this helps.

Darren