I have a nordyne furnace running on propane. It is about 15 months old. Furnace goes through normal start-up. Inducer fan runs, approximately 30 seconds later the flame comes on, main blower never comes on. Flame turns off. About 30 secs after flame is off, main blower comes on and stays on until I reset the inducer pressure switch. Any ideas?

Sounds like the flame is turning off to soon for furnace to reach temp. needed for blower to come on,, do you have a meter to check for power going to the blower motor?, does the furnace have a flame senser ? It may need cleaning,with steel wool or fine sandpaper

Does your furnace have trouble shooting LED light that emits a code signal.

MY thought is that you limit switch may be opening and turning off the burner and the heat in the furnace keeps rising until the inducer pressure switch clicks open, causing you to have to reset it.

So maybe you need a new limit switch or at least one with a higher limit.

Let me know what you find.