I can hear the fan kicking on and running how ever no matter what nothing comes threw any vents at all. Also it only works on high. My truck is a 89 f150 4x4 I6

 

You sure it's not coming out the defrosters? That's the default setting when it fails so the windshield can still be defrosted.

 

Nope nothing there

 

Better make sure the squirrel cage didn't break off.

 

Pulled the motor out and its all there, clogged up evap core?

 

If the blower motor resistor fails - will typically only have high speed.

+1 on the squirrel cage, especially if you don't hear any air moving at the intake cowl. Easy enough to pull the blower motor and have a look.

 

Air doesn't go through the evaporator when on heat. Make sure the cage isn't freewheeling on the fan shaft.

 

Yep, could be a clogged evap core. Also, haven't had the problem on this truck, but on vehicles with more open-slotted outside air intakes - leaves and crap have blocked the air inlet to the blower.

 

You don't need the outside air intake when on recirculate.

 

Make sure the selector switch is working. Have someone watch the motor as you cycle through the dial.