Weird gas fridge issue

Thanks for the help. I kinda thought air might be the issue. I will check the flame color when we leave on Monday for our next trip. The funky thing is that it only fires up after the very first use of the furnace, early in the morning. If I try lighting it midday when the furnace is on or off it will not light. . I'm bummed because it was fine until I flipped the gas sensor off in the middle of the night, hence cutting off the gas flow.