Weird, I have air blowing out onto floor cant change it with the controls. Pulled off HVAC actuator and able to move the control rod by hand easily so I Put on new HVAC actuator motor, still nothing. a/c compressor doesnt even cycle like it used to, cant get it to cycle by jumping accross low pressure switch. I have no juice going anywhere in the under hood a/c circit, none to compressor or accumulator. A/C button and recirc do not light up when pushed in. Checked the relay, and all fuses and they are perfect. I disconnected battery and left door open for 20 minutes and hooked everything back up NO Change. The actuators for vent defrost and floor, as well as temp control actuator do have power to one wire, when contols are moved none of the other wires light up my test light. Would it be dash HVAC controls ? Damn I got to get this fixed. If I pull my HVAC motor off the vent floor, defrost actuator and leave it off will it hurt anything till I can figure this out ? HELP !!!!!!!!!!!!!!!!!!!!!!!!!!!!

Mine has begun doing similar. It works as ordered for 30 - 45 minutes of travel, then just dumps all air onto passenger floorboard and none through vents.
It resolves after truck is parked for 20 - 30 minutes, but begins again as before.

I'm actually leaning toward a vacuum leak.
Might even be tied to my low power and black stacking. (???)

I hope there's a cheap fix for this.

I dont know If its a vacume leak for me or not I think My system is all electric as far as controls and such I cant see any vacum hoses going itnoc ab at all especially near heater etc.

At least you have some air flowing. Mine was realy intermittent, like 90% of the time inop, So I replaced the rheostat, and now it does not work at all.

your system is electrical, not vacuum.

You say 'the' rod moved, there should be 2 of them. One going to the vent flaps, one going to the top. IF everything moves, then unmount the motor and see if the motor itself is working.

Both rods move free and easy, new motor only moves fraction of an inch each way like less than 1/8 ". so Im thinking dash controls ?????

The power for the HVAC control head and relays should be routed through a circuit breaker rather than a fuse. Look for a small aluminum box plugged into the fuse panel (may be more than one) and check it for continuity.

it is probably the head control. it was the case on my 95 and 98.