I tried to start up my furnace this weekend and I got 1 click and then a 2nd click and the error code for pressure switch.
I need to know what my next step is to disgnose the problem and get it running since the temps are dropping to just above freezing at night now.
I had the blower motor replaced 1 1/2 years ago.

Something is obstructing your flue pipe, most likely something simple like leaves or a wasp nest are very common. Let us know if you find anything.