1998 Jeep Cherokee XJ 4WD 4.0

My heater core broke so I replaced the heater core, ac evaporator, blower motor, relay, and resistor.
When I put the box back on and turn it on i can hear the fan working but nothing is coming through the vents

 

Did you check the vacuum lines and all the doors that they control ?

 

the lines seemed fine, I think all the Vacuum Actuators (i think thats what they are called) went bust

 

Check the hose that goes thru the firewall. Chances are it's broken there.

 

OVERDUE UPDATE:
Turns out the power can plug into the fan both ways.
I had the plug plugged in the correct way which had then fan blow in the wrong direction, plugging the power in backwards into this particular fan allowed it to spin in the correct direction

 

Very strange. I've never dealt with my blower fan but I would have thought the connector could only go on the right way. Good to hear it was a simple fix, although I can imagine you spent a lot more time before finding it.