Front a/c not working Ford expedition

I have a 2004 ford expedition. The front vents are
blowing hot air when the a/c is on but the back
vents are cold. I had the actuator replaced and it
didn't work. Then we checked the blend door
which didn't seem to be moving and propped it
open... Still blowing hot air. I'm not sure what else
to look into. I wasn't sure if I should try freon
because I figured if it needed it the back would be
blowing hot air too but it's still ice cold. I just
bought this car but can't drive it much because of
it being too hot. Please help if you can