I have a 94 F350. Last night on the road it started making a deep roaring noise while letting very little air through. It was extremely loud. All that was open was AutoZone. I stopped and changed it in the parking lot. I noticed on my blower wheel two of the fins were broken off, but they didn't have one in stock. I put my wheel on the new motor. Still a deep roaring rumble with very little air. Any ideas?

 

Missing fins can definitely cause lower air pressure, and will also imbalance the motor.

 

I can't find factory a/c wheel anywhere. All people stock is dealer installed a/c wheel? Very weird

 

Rockauto has them.

When your new blower wheel arrives and you have the motor out, I'd take a look with light and mirror over into the A/C evaporator case, and see if you find the pieces, and if crap is up against the fins. Can vacuum it out if you make some simple attachment for a vac to reach in there. Any crap that made it through the blower wheel came from the air intake path. On a 1994, the cowl vent in front of the windshield is small holes, not much can get through those, unlike the old big slots.

But there is another path. Rain going into the cowl vent has to go somewhere, which is left and right over the edges and down behind the fenders, where there is a rubber "Duck Bill" one-way valve. Supposed to let water out, and close. But age can destroy the rubber, and mice/rats can eat through it to make a nice nesting place in either lower area. Then stuff can get sucked up into the blower.
Pretty difficult to see the duck bills, underneath, behind front wheels, behind the bottom lip of the plastic inner fender, have to reach up and feel around. Not easy at all to find or see. Shake hands with any critters you find there

 

I buy a lot of parts from Rock Auto, but they weren't going to help me in this case. The whole point was to find a store with one in stock since my a/c broke down while on the road. The high got up to 120° that day, and I wanted my a/c. Haha I ended up finding one at a Napa 99 miles down the road. I replaced the wheel, the motor, and the resistor (which had been bad for some time). I got the broken pieces out of the heater box. The new wheel is metal. Big improvement.... works like new