The air flow direction is controlled by what is called a mode door actuator. On this vehicle, all actuators are controlled via engine vacuum which is supplied from the engine intake manifold via a black vacuum hose. That hose connects to the rear of the controller in the vehicle where you select air flow directions. Then, based on your selection, engine vacuum is routed to the different mode actuators which open and close different doors allowing the air to flow in different directions.
Since you are getting air at both the defroster and the floor, I suspect the vacuum supply from the engine has failed. In most cases, the plastic hoses crack and break off. So what I need you to do is simply craw under the dash and locate the vacuum hoses to the rear of the controller. Locate the black supply hose and remove it from the controller. Start the engine and place your finger over the end of that black hose to see if there is a vacuum (suction) available from the engine. If there isn't, we will need to locate where the break has happened.
I attached a pic below that shows the different actuators and vacuum lines. Note that I highlighted the supply. That is the black one you need to check.
Let me know what you find or if you have other questions.
Wednesday, June 17th, 2020 AT 7:00 PM