Red Light Blinking on Furnace Blend Air

The red light blinks and the alarm sounds on the blend air in my motor home when the air conditioner is on and turning the switch off for 5 minutes usually fixes it for the time being.

The fan is mounted on the trailer roof, not in an attic.

I don't have a book on this furnace to check trouble shooting ideas.

What is the problem that it does this and then is okay for weeks at a time?