The furnace in my vacant rental property does not light. The blower runs but the igniter never glows and the gas valve does not open. The LED blinks once which means the burner limit circuit is open.

How do I replace the burner limit circuit?

Inside the furnace cover I found the electronic gas valve, the main controller, igniter, burner, combustion air blower motor, pneumatic blower switch, etc, but could not find a "burner limit switch". What am I looking for exactly?

I can't afford an expensive visit from a repair guy as I am doing this on a shoestring budget.

The furnace is in very good shape (6 years old) and clean, sounds like a single faulty switch. Thanks!