If pressure switch will not open what do I need to do

Remove the air tube going to it and see if there is any water in the switch. You can blow threw the switch just do not use much force of you will mess it up.

hwalker, just to make sure we are on the same page, are you saying your pressure switch is stuck closed? Or will it not close? Start with Joshes advice, if no water is present, then you will have to replace the pressure switch(if indeed it is stuck closed). You may be able to unstick it by sucking and blowing lightly, but if it has stuck once, it will most likely stick again, best bet is to replace switch

The pressure switch is a safety control and should not be assumed to be bad , proper trouble shooting may prove a different problem exists ,good luck.

hwalker, please let us know what is happening with your funace, and if you have the skills to trouble shoot it. We will try our best to help you avoid unnecessary part replacement.