Furnace starts out great & then later not?

Blanco1 wrote:
Two trips in a row now are furnace starts out great!
Lots of heat & by morning when we wake it blowing cold.

Can anyone help me fix this?

Suppose to another cold night.

Faulty sail switch causing the propane to cut off at some point during the night? Perhaps the terminals are corroded and when they heat up and expand they lose contact, cutting off the propane.