Inspected a York furnace today. 80,000 BTU gas-fired with model P3DNA12n06401B.
The evaporator coil is underneath the unit and airflow through the duct system is reversed. The return ductwork attaches to the top of the unit and air blows through coming out of the supply ducts at the bottom of the system. I have never seen this before.
I can't determine if the unit is rated for this.