A while back someone posted some good information in a thread on how to use a manometer to diagnose problems with a furnace heat-exchanger, pressure switch, or inducer motor. I'm hoping that person can share that information again.
The poster explained how certain pressure readings at various locations in the combustion system could indicate problems with restricted intake, restricted exhaust, cracked primary hx, cracked secondary hx, bad inducer, or bad pressure switch.
For example, how can you tell if a bad inducer motor is preventing the pressure switch from closing or if it's a leaking secondary hx?