I have a 1979 Rheem furnace that turns on and off constantly. Any ideas on how to trouble shoot this. Purchased a new load limit switch and that is fine now.Help, please.

What is turning on & off? Is it the burner, fan, or both?

At 35 plus years old , unless it has been extreamly well taken care of and inspected regularly , it should be replaced, just my thoughts and opinion,

At 35 plus years old , unless it has been extreamly well taken care of and inspected regularly , it should be replaced, just my thoughts and opinion,