I found a couple pix regarding the outside/inside air mix. BTW, one of the pix below shows a min. of 20% outside to 80% inside. It is controlled by a vacuum actuator that HAS to be working for you to get inside air.
So, if your ONLY HVAC problem is this, look up under the dash on the passenger'* side, look for an ORANGE vacuum line that goes to the Outside (OS) Air actuator. If it has been knocked off, this may cause your problem. Before you do that, though, read all the way to the bottom.
Here is that portion of the system below (circled)
A more common thing
to happen is for a loss of source vacuum to the HVAC system. But another symptom of that is your AC blows out of the defrosters instead of dash. In this case, look for a vacuum line knocked off under the hood at/near the vacuum tank on center firewall, closer to driver side.