I arrived to a customer no heat. Customer was mentioning that the furnace blower was running and the inducer was going but no heat was coming out. During inspection I got three flashes from the control board which would indicate a pressure switch not closing while inducer is operational. I found the port for the draft inducer assembly to be plugged up. I informed the customer of the issue and she has purchased a blue membership. I performed furnace tuneup and cleared out the build up that was in the port. I checked all amp draws voltages gas pressures resurfaced flame sensor igniter is within spec blower capacitor is in spec blower wheel is clean or motor is showing no signs of leaking oil and is amping properly. I cycled the system several times with all operations being normal.