My furnace will not kick on to heat. I have 3 blinking red lights saying the pressure switch is stuck on open. How do I fix this?

Test the pressure switch and if really stuck open and will not close replace with the correct pressure switch for your model and brand of unit.

My pressure switch light indicating open was on and the furnace would not come on, the problem was abundle of wires above the inducer motor had a couple that were draging on the very delicatle balancing do dah that hangs on the inducer motor. Once they were wire tied out of the way the delicate thing could move free and the furnace works again. The tip off was trying to spin the fan inside the inducer it should spin free this one only would rotate less than a half rotation then return to starting position, M;Liss