Travel Trailer Propane Heater Not Working

[alapataws]

This past spring we took the camper out and it got a little chilly so we turned up the thermostat and the propane heater clicked on and worked as it always had. Last week we came over to Boone, NC and the temps dropped down to 49 degrees so I turned up the thermostat but nothing happened. I could hear a click in the thermostat when it hit its target temperature, but the heater fan never came on. We are plugged into a 30 amp outlet, however I do know that my travel trailer battery is dead. Would this be the cause of the heater not working. I hooked up the seven prong plug-in into my truck, and it still didn't come on. Does the heater have a device that requires a battery to start even though we are plugged in. If the battery is not the reason, what could be the cause of the heater suddenly not working? The fan does not even come on.
Thanks, J.K.

[alapataws]

Well I found the problem. The cycle adjustment arm in the thermostat was in the dead space and not touching the wire. once I moved the cycle adjustment arm; the thing that looks like an arrow on the round center piece inside the thermostate cover, wala, the heater fan came on and then shortly after it ignited and blows hot air.