Originally Posted by Wuzzat?
Get the specs for the switch and simulate the setpoint pressure by using a column of water. You'll need some tubing from the hardware store, and a meter.
If it's like 0.05" WC [about 3/64"] you may want to put a drop of hand dishwashing liquid in the water. It breaks the surface tension so you get a more accurate reading.
Or you can slope the tubing which will amplify how visible this 3/64" is. A 10 degree slope will give you a 17/64" difference.
From Grainger, roughly half of their switches cost between $44 and $26.
Ordered a new switch and will arrive tomorrow. Will update.
My new pressure switch arrived.
Put it to replace the old one.
The furnace back to work.
Thank you guys for the help.