Goodman Furnace
Model #GMP075-3 Rev B Serial #9703821053 The Red LED on the control board blinks 4 times.
Cleaned it entirely with compressed air. Light indicates limit switch open. Not sure what that is or where it is located. Diagram shows red wires. Behind the gas control, there is a long device that inserts above the burners with what looks like a dime at the end of it.
It this it? Does it need to be replaced