Forum Discussion

RedRollingRoadb's avatar
Aug 25, 2014

Sail Switch or Something Else?

Suburban SF-30F about six years old. Problem has been ongoing for several years but now has hit critical.

Every once in a while over the years the unit would fail to light, shut down, I would turn off and let it reset. Sometimes it would start, sometimes not. Take the grill off, bang around and it would fire up. Sometimes it would cycle 3-5 times then fail to light. Other times it will run for days and not give a problem.

Batteries are good and charged and it makes no difference if on shore power or not.

My first thought is sail switch, but the fact that banging around in the cabinet or driving makes me wonder if something else.

I don't mind throwing some parts at it since I need to pull it anyway but any ideas?

I am guessing that the intake/exhaust tubes are kind of a press fit into the exterior ports. Am I correct or is there some sort of gasket that I need?

8 Replies

  • That could mean that the ignitor is too far away from the ground point.
  • Yes, "fails to light" suggests that the ignitor is "clicking". If so, the sail switch HAS to be good. If the sail switch is bad or for any reason it does not complete the circuit (low voltage, restriction in intake or outlets, etc), it will not allow the PC board to open the gas valve or fire the ignitor.
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    Several possible issues.. You said it "Fails to light"

    Mine did much as yours twice the second time by listening to it (Epically from outside) I could tell it was lighting, The problem was IT did could not tell it was lighting. Had to replace the control board with a Dinosaur borads replacement, (Way better board)

    The first time I found the spacing on the spark gap was a touch excessive.

    My parents had an oil fired furnace in their house..... Same problem.
  • I had a brand new trailer with a never-been-used-by-me furnace that would not light up. Took to dealer and it was faulty main gas valve. Anything in the gas delivery/ignition systems is suspect.
  • When you get it out, make sure the fan spins freely with out scrapping on housing.
    I would then look closely at the ignitor and flame sensor to insure it is adjusted correctly.
    Check for any loose connections. It could have corrosion and sometimes arcs through and works.
    Intermittent lighting will be difficult to find. I doubt whether it is sail switch.
  • I had trouble with my furnace (sorry don't remember model #) and found the ignition electrode was a little to far from the ground and would sometimes spark and sometimes not. Cleaned it up and bent it so it was a little closer and no more problem.
    Brian
  • Sure sounds like a sail switch sticking (periodically) to me.
    That's where I would start.