Dirty flame sensor, and no fresh air.

One flash. Let's see what that is. That's so small I can't read it. One hour lockout. So why is it a one hour lockout? See that draft motor? It's missing the housing around the end and up there. Tells me it's not doing a real good job of sensing the flame. I think that's supposed to be a solid LED. Pull that flame sensor. Ooh it is hot. Better try again. LED up there to see if it stays. Insulation, that's why I did that.