circuit boards fail on these things a lot. Could also be a defective sail switch. Very easy to change and cheap too. On my newer motorhome the furnace would do the same thing. I made appointment for warranty service but it started working before I made it there. this has happened several times now on different trips. The dealer will not fix it if it's working and I hate waking up cold in the middle of the night. So I blew out the the dust with compressed air and replaced the circuit board, sail switch and overheat sensors since they were cheap and easy. So far so good knock on wood!
2018 Chateau 24FS