Arrived to remedy an inoperable system. Upon inspection of the furnace found fault code 223 present. This indicates the pressure switch is not sensing the draft in the exhaust. Performed diagnostic and found that there is port to the pressure switch on the inducer is clogged. This is a sign of age with this furnace, as this port accumulates debris while the system runs. With homeowners approval signed them up for the maintenance plan and cleared the blockage in the pressure switch port. Tested system operations to ensure the system will continue to function properly. Furnace is operating properly upon departure. Realized at the last minute that I neglected to dispose of the old furnace filter. I apologize for leaving that sitting out. Thanks for your time today.