Atwood 8531-IV Furnace won't click

[Bill 39]

The Atwood 8531-IV furnace in my 5th wheel is not igniting. Last year I had trouble with it. It would click three times, light and not stay burning. I found out the burner head was shot so I replaced it and the electrode and it worked fine. After not using all summer, we fired it up on a cold morning. It lit and burned just fine. After it reached temperature the heat shut down and the fan kept going. It would not ignite again. When I start it up there is no clicking. The circuit board is giving a flame sense fault. All the videos and troubleshooting starts with the igniter clicking. What could cause the lack of clicking? I've changed the sail switch and the thermostat. The solenoid gas valve reads that it is working correctly. The circuit board seems to be working (diagnostic light works, fan/blower works). Any help here?

[Old-Biscuit]

After fan starts and does the purge cycle the sail switch/limit switch circuit sends DC to circuit board
Circuit board then sends DC to gas valve AND SPARK ELECTRODE at same time

No Click......spark electrode not firing
Either electrode is sooted/carboned up (dirty)...clean using emery cloth
Spark gap is wrong...should be 1/8" gap (3/116" MAX)
Electrode wire connection loose in ceramic insulator---replace


If not spark electrode then circuit board 'spark circuit' is bad

You don't mention Year of RV
If Older model.......you will have a Time Delay Relay
If not older model you will have circuit board that incorporates the delay function (for purge)

Here is a KIT Instruction -----------am only inclosing to show the wiring diagrams for the 2 versions (not for the converse kit)

https://techsupport.pdxrvwholesale.c...-Doc-38677.pdf