Upon arrival I completed diagnostics and found the fan motor outside had stopped running. I replaced the fan motor and went to check the DT and found it at around 13 degrees indicating the system had an issue. The supply plenum has a lot of takeoffs taped closed preventing proper airflow. Coil is rigged in position and is a slant coil. Found furnace running with no filter. Found the evaporator coil pouring water onto the floor from the left side of the furnace as well. I was told that the customer would take care of the water issue as they were in water and fire disaster cleanup as a profession. Also found the flue pipe from the furnace changing sizes twice and venting into the basement which is dangerous and could be deadly. System has partial cooling at this time but will freeze up eventually. DO NOT RUN THIS FURNACE WITHOUT IT BEING PROPERLY VENTED TO LOCAL CODE