Woke up in the middle of the night a little chilly. I heard the furnace fan running but cold air was blowing. Additionally the fan was not shutting off, not good if we were boon docking. Those fans use a lot of power to be running continually. I shut off bedroom furnace and went to plan B.
Today I pulled a mud dauber nest from the exhaust tube. It was the size of a small egg. All is well in "Mudville"
Pulled one out of a friend of mine's just the other day.
They make screens for hwh & furn. I used them when in 'dauber country', worked well, even though some mfgrs don't like them.
Amazon.com: Camco Flying Insect Screen -Protects RV Furnaces From Insects... (https://www.amazon.com/Camco-Protects-Furnaces-Insects-Prevents/dp/B00192JFBI)
I bought some aluminum screen at Lowes and covered the entire opening on my old coach that was after I had to disassemble the entire furnace to get to dauber nest that was around the bend in the intake air. I put screen on hot water heater and furnace, was still working fine when I sold the coach!
Chris