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Straylight's avatar
Straylight
Explorer
Oct 24, 2018

Can't figure out Atwood furnace no ignition

Make and model: Atwood Hydroflame 8525-IV

Complaint: Furnace clicks but fails to ignite, then goes into lockout mode after three attempts. Control board has green light, turns to red during ignition attempt and then back to green after failure, then no light when in lockout.

Parts cannon so far:
  • New control board (Dinosaur)
  • New ignitor/flame sensor unit (OEM, with new high-voltage cable)
  • New propane regulator

Interventions/checks so far:
  • Battery voltage at ~12.7v, and furnace will not light on shore or generator power either.
  • Removed and probed sail switch and found continuity between contacts when sail was depressed by hand (multimeter in continuity mode gave steady beep). Brushed sail switch contacts with wire brush and pencil eraser and reinstalled. No change.
  • Blew out propane line with compressed air, propane tank is full, water heater is currently running on propane and stove has been used repeatedly; note that problem still occurs if water heater is off. Fridge is also running on propane without a hitch. I smell slight propane smell at furnace exhaust when it tries to ignite.
  • Removed and cleaned burner chamber thing; minor rust and deterioration.


Any ideas as to what to check next?

13 Replies

  • if you are getting a bit of a smell of propane on the exhaust when it tries to start , gas valve should be ok, try taking off the high voltage lead off where the burner is and placing it close to the metal frame and see if it sparks when it tries to light or not. Had mine do the same last week we had it out, it was a bad Neon (NE2) lamp near the High voltage coil fixed it …
  • " I smell slight propane smell at furnace exhaust when it tries to ignite"

    Bingo. Your burner is either dirty or the spark electrode is not adjusted to spark between the burner and the electrode. Odds are the electrode is sparking to the top of the combustion chamber which will not ignite the LP. Doug

    PS, from what you have done, you are qualified to be a Mobile RV tech:B
  • While it is clicking check to see if there is voltage from circuit board to the gas valve.
    Another is to verify that the two coils on the gas valve have continuity.

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