My furnace will not come on. The LED flashes 3 times, which tells me the venter is plugged or my pressure stch is open. I bypassed the pressure switch and everything works fine. I installed a new pressure switch and the furnace came on as normal and the LED stayed on as it is meant to. I put the covers bck on the furnace. Te next evening I turn the furnace on and the same thing happened... LED blinks 3 times... pressure switch not closing... I can bypass it again and fuace works. Any suggestion?

The inducer motor(vent motor) closes the pressure switch. It checks to make sure your vent is not restricted. On a 90% furnace if the exhaust vent, intake or condensate drain is restricted the switch will not close. NEVER BYPASS A Safety SWITCH. Give more info about your system if you can.

I just had a new condensate pump installed. That's when my problem stated. Is it possible that the drain was not properly connected?