AC/heater blower reduced air flow
Van 1988 Dodge B350
360 motor

Got the Heater /AC fan motor replaced . but even before I replaced it I noticed the air was not blowing very hard out of the vents.
The fan seems to be running full blast, but with little air flow out of the dash vents.
It's like the cabin filter was plugged up. Only from what I see in the service manual there is no cabin filter.
Could the air box be plugged with leaves?
The AC blows very cold air but it's like the fan is on low. Only you can clearly hear it's running on high.
Any suggestions ?

Its running backwards. Switch the wires at the motor.

There could be a mouse or squirrel nest inside the plenum.

As you thought, there are no air filters. However, there is a design element which could lead to a restricted airflow; the heater core and the air conditioner core are sandwiched back to back. If anything like for instance leaves, lint, or dog or cat hair got sucked up into the air intake, having the two sets of heat exchanging fins in line assures a 100% capture and partial obstruction.

You might also want to check to see if the actuator for defrost mode is sticking... That would divert a large proportion of the air up at the window. It's located on top of the air plenum behind the radio.

Are you aware of the push/pull function of the push button climate controls? If you only push the buttons, you get essentially a reciculate mode, which doesn't have all that much air flow. If you push the button in, then pull it back out, that engages the fresh air mode, which can be like a hurricane by comparison.

It appears this was the problem. I cleaned off the connection switched wires and It;s blowing twice as hard.

Only the wire connector ran very hot . That's why I cleaned it up. Could the line resistor block be going bad.? I forget what it's called.
I'm not real sure where that block is , I'll look in the repair manual.