[JimKrieger]

Answers to all the great questions:
My vertically oriented furnace is only accessed via the basement with circuit board, etc. facing and near the floor above and next to the outside wall which has no access panel. The RV is on shore power. All 12 volt lights work fine. The gas/electric refrigerator works fine. The gas stove quickly ignites. All AC outlets and lights work fine. No fuses are blown and no circuit breakers are tripped.
(1) I set the furnace for a very high temp. (2) The fan comes on and stays on. (3) I then hear what I assume is the gas solenoid after about 15 seconds. It clicks once but there are no repeated clicks of the igniter. (4) About 15 seconds later, the gas solenoid clicks again. (5) About 15 more seconds and the gas solenoid clicks again. (6) The fan then shuts off and doesn't allow to come on again until some longer wait time passes. (7) I go to the outside exhaust and faintly smell gas. To me, it seems the ignitor never gets power. I wouldn't expect dirty igniter electrodes to prevent its clicking. My untrained guess is for a bad igniter, limit switch, bad sail switch or circuit board. If I have to remove the whole unit, I'll clean it and replace all but the igniter to try to avoid having the hassle of removing the furnace from the unit and disconnecting/reconnecting all the ducts again. I'm in South Texas for some months, so only need the air conditioner which is working well, thank goodness.