I have a York 90 plus furnace, the red light was blinking 3 times, I pulled the wires off the condesation pressure swithch and placed a jumper in the wires the blinking lights stopped and the furance kicked on, can I leave the jumper in till it get the part?? Is it safe to do leave the jumper in??

No, not safe at all. Odds are, its not the actuall pressure switch that's bad (but its not out of the question). A restricted vent, or plugged drain system on the unit would cause the pressure switch to not close. The pressure switch is a SAFETY device that prove the unit is exausting correctly. If the vent is obstructed, or the drain lines or trap become partially plugged, it will not allow the unit to fire due to backup of water. You can take the drain hoses off and blow through them, and the ports they are hooked to. This will clear any blockage of the drain system. Also, take the tube from the pressure switch to the draft inducer off and blow through it, and clean the port on the draft inducer where the hose hooks to.. A paper clips works well for this. You most likely have two pressure switchs, so clean all hoses and ports (except on the pressure switch itself, you don't want to suck or blow too hard, or stick anything in there, as it may damage the diaphram. Good luck and please let me know how things work out.

I removed the hose to the Condensation Pressure switch, blew through it , then connetio the end to the pressure switch and lightly blew into it, disconnected it and connection the other end and lightly blew into it, reconnect the hose and wires going to switch and it worked fine. Is this a indication that the diaphram is going bad and should be replaced?? Thank you for the information

Well, did any water come out of the hose? It shouldn't, if it did, it indicates a plugged drain system. Now, pressure switches are fairly cheap, and they DO fail from time to time, so yes, It wouldn't hurt to get a new one. Let me know how it all works out, or if you have any more questions. I only get on the computer from time to time, so sorry for any delays in responses.