It is called 'limiting'
Furnace High temp limit switch is OPENING (shutting down furnace) then cools off CLOSES and furnace restarts
Could be bad High Temp Limit Switch (have to pull heat exchanger to replace)
Could be restricted air flow.....either in discharge side OR in return side (area around furnace needs to be free/clear for return air flow and registers open/ducting un obstructed for discharge)
Could be furnace 'over-firing' ( propane pressure too high....S/B 11" WC )
2007 Dodge 3500 w/Tractor Motor & NUWA 5vr
FT traveling Jan 2007 - Jan 2014
Still DEBT Free