surburban furnace will not light
sf -35 # 963105899 in 97 allegro bus. Furnace goes thru steps but does not light. I have 12 volts to relay, temp sensor, sail switch , to circuit board. Fan runs ,But I do not smell propane out exhua...
Forum Discussion
You have 12V DC power from t-stat to fan thru sail switch, high temp limit switch and to circuit board but no spark/gas valve.
Check for 12V to the gas valve during the opening cycle.....typically 15 seconds after power reaches board. Power is applied to gas valve for 7 seconds while ignitor sparks.
No power to gas valve.....clean circuit board connection
Still no power than circuit board is problem
If you have power to gas valve than ignitor circuit is problem
Bad connection on board for high tension wire....bad high tension wire
Ignitor spark gap/position incorrect (3/16" from back of lance, centered over burner with a 1/8" spark gap)
Suspect you will find no power to gas valve....circuit board.
Suburban part number 520820
Check for 12V to the gas valve during the opening cycle.....typically 15 seconds after power reaches board. Power is applied to gas valve for 7 seconds while ignitor sparks.
No power to gas valve.....clean circuit board connection
Still no power than circuit board is problem
If you have power to gas valve than ignitor circuit is problem
Bad connection on board for high tension wire....bad high tension wire
Ignitor spark gap/position incorrect (3/16" from back of lance, centered over burner with a 1/8" spark gap)
Suspect you will find no power to gas valve....circuit board.
Suburban part number 520820
