Forum Discussion

redneckracing's avatar
redneckracing
Explorer
May 02, 2015

Furnance runs but doesnt ignite

I left the heater on one night but the gas was off. It was parked outside my house. Anyway, we went camping the heater wouldnt work. Fan runs but does not ignite. I tore it out of the camper. Tested EVERYTHING i could.

Sail switch: GOOD
Limit switch: GOOD
Time delay relay: GOOD
Gas valves: GOOD (Energized and they do click)
Thermostat: GOOD

There isnt any power to the gas valves, when there should be. Check power at module board. Power going in but nothing coming out to gas valves. I ordered a module board because i do believe that is the problem.

Am i correct?? Thoughts?? Suggestions??
  • scrubjaysnest's avatar
    scrubjaysnest
    Explorer
    May 03, 2015
    One other thought, if you can hear the spark and it isn't lighting there is a little gas loving spider that will plug the orifice into the burner. Have to pull ours out of the other camper for this problem about every two years.
  • redneckracing's avatar
    redneckracing
    Explorer
    May 03, 2015
    Unfortunately our heater and a\c have to seperate controls. Its too old to be together. The thermostat is in the rear of the rv and the ac unit has the controls on it, itself. Luckly for us, the first owners had a heater strip installed on the ac unit back in the day and it heated the camper to 80 degrees. But i dont want rely on that because itll be the next thing to go out.. Lol
  • YnotTurbo's avatar
    YnotTurbo
    Explorer
    May 03, 2015
    We had this happen. There was a switch in one of the a/c units that had to be turned on in order for the furnace to work correctly... Not sure what switch, but the technician turned it on and the heat worked.
  • redneckracing's avatar
    redneckracing
    Explorer
    May 03, 2015
    Yes, ive bleed the lines. About 7 times actually. I tried to blow thru the propane line (while on the bench) and i couldnt blow thru it. Energized and gas solenoids and i could. I have tested everything. I checked all power switches etc. I turned up the thermostat and checked for power at the board. The test light lite when it was supposed to. Power in but no power out.. I'm 99.9% the board was bad, but always second guess myself. Thanks for your help!!
  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    May 02, 2015
    DC power goes to gas valve for 6-8 seconds during the same time high voltage is sent to spark electrode (DC power remains on gas valve AFTER flame proved)

    The power is sent only after:
    Fan runs (time delay)>>>>>>>sail switch/limit switch make up

    IF you have power making it all the way to the board via the sail/limit switches and no spark/power to gas valve than Control Module (power board, circuit board) is bad.
  • midnightsadie's avatar
    midnightsadie
    Explorer II
    May 02, 2015
    well ,did you bleed the propane off? light the stove let on a minute or two, did you check to see IF there is propane. I think you did a lot of work , but you should check the very simple things first.

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