Mine operates this way: Set the thermostat to "Heat". The blower motor should start running. The blower should move air over a small flag called a sail, which operates a switch, called the sail switch. The sail switch starts a timer running in the ignition circuit. I'm not sure what that time is but it is meant to insure that there is no residual gas in the fire chamber when ignition is initiated. When that time expires, you should hear a definite click. That will be the gas solenoid opening up. I assume that if your blower is running you have enough voltage to open the gas solenoid. With the gas valve open, you should also get an ignition spark and you should see a blue flame in the small window on the front of the furnace
. I can see it through the grill on my furnace. This whole process may take about a minute. If mine does not light
on the first try, I believe it will try again two more times. Then it will go into "Lockout" and you will need to turn the thermostat off and back on to try it again.
When the furnace does light and the temperature is satisfied, the flame will go out but the blower will continue to run for some time, maybe 30 seconds to a minute. Again, this is to insure that no gas remains in the combustion chamber which could create an explosion hazard on the next ignition cycle.
Make sure you have good gas pressure. Make sure the fresh air inlet and the outlet on the outside of the camper are fully open, not clogged with spider webs are leaves or grass. Good luck.